Intro:
As I've mentioned before, personally my eSATA needs are simple (typically single drive use w/HD docks - no PM/high end enclosures/RAID arrays, etc). I've gotten by fine with low-cost eSATA cards (typically $20 range) and until ordering the NewerTech 6G card, I've been using a Sil3132 based 2 port (1x) PCIe card in my Mac Pro, which as you know requires a driver install (and like most all 3132 based cards except for the more expensive firmtek models, the current SI 3132 drivers are 32-bit only - card isn't usable with 64bit SL boots.) However when this NewerTech SATA 6G card was announced (natively supported incl. 64bit SL) at $59.99, I was interested in replacing what I have now. This isn't a high end/expensive card (and doesn't support Port Multiplier enclosures), but considering its native support (plug and play basically), better controller chip and reasonable cost - it's a very good fit for my needs. (I don't own any PM enclosures and don't have any plans to in the future.) Although site sponsor OWC offered to send a review loaner, I felt like I'd want to keep it, so I decided to buy one. And I also ordered one of OWC's ($59.99) dual-drive eSATA-only enclosures for tests with a couple WD Caviar Black's I had on hand to at least have a bit more performance headroom than the HD docks I typically use. And being eSATA pass-thru, it rules out any issues with the bridge board used in multi-interface enclosures. (Although I am a big fan of HD Docks - easy to swap in bare HDs used for backup/TM with various macs w/o the need to open a case up or have several ext cases around.)

NewerTech eSATA 6G card: What's Included:

The card is smaller than I expected (even smaller than the 3132 card). A low-profile bracket is included, but not needed for installs in machines like Mac Pros. Here's the specs from the product page (updated for revisions Friday afternoon):

• Type: SATA 6Gb/s
• External: Ports 2 x eSATA
• Interface: PCI-Express 2.0 x1
• Form Factor: Low Profile Ready
• Data Transfer Rate: Up to 500MB/s per port (up to 500MB/s total for x1 PCIe 2.0 slot or 250MB/s total for x1 PCIe 1.0 slot)
• Operating Systems: Out-of-the-box ready driverless install for Mac OS X 10.5 & 10.6, Windows Vista & Windows 7, and any Linux version with built- in AHCI support.
• Booting: Supports booting in Windows (Vista & Window 7) with AHCI mode enabled in the BIOS. Does NOT support booting on any Macintosh platform. (BTW - I cloned my 10.5.8 Internal HD (using DU 'restore' feature) to a drive in the eSATA case connected to this card - powering the Mac Pro up w/Option key held down did not show the eSATA HD as a boot option - although OS X's startup disk control panel did show the cloned eSATA drive in the list. I did not try selecting it as a SU disk that way though.)
• Compatible With: Mac Pro early 2008 to current (Model ID 3,1 and 4,1) and PCs that have an open PCIe 2.0 slot, Mac Pro (Model ID 1,1 and 2,1) that have an open PCIe 1.0 slot
• 1 year warranty

The Features list on the product page mentions eSATA hot plug support is dependent upon external enclosure compatibility. (Someone had asked about that.) The manual notes it's Marvel 8891x based and it's been plug and play in both OS X and Windows here (as promised). Since it wasn't mentioned on the product page originally, I assumed it didn't support PM (Port Multiplier) enclosures. (Again, not an issue for me as I don't own any PM cases) Here's Larry's (head of OWC) answer to my original email - I wrote to confirm no PM support:

"Correct - this current card doesn't support Port Multiplication.
It does work with multi drive eSATA solutions like the NewerTech Guardian MAXimus, Elite-AL Pro RAID, and Elite Qx2 solutions which feature eSATA but do internal RAID control of the drives."

Update: OWC has now revised the product page to note no PM support.

Works with ANY eSATA interfaced equipped external hard drive or optical drive (NOTE: does not support port multiplier cases/enclosures.)

(I wasn't not sure about Windows/PM support - some natively supported cards like the JMB36x expresscard I have list PM support in Windows but not with OS X. But safest to assume not and I have no PM case to test with windows.)

Test System/Hardware Used:
I didn't have any SATA 6 Hard drives on hand, but did have a couple 1TB Caviar Blacks. (Which IMHO are a great value for about $100 each on sale.)

• Early 2009 Mac Pro (Dual 2.66GHz CPUs), 12GB Ram, GTX-285, 4HDs (10.6.2, 10.5.8, Vista Ult/64bit, Win7 Pro/64bit), dual optical drives. Benchmarks run while booted to OS X 10.6.2.
• eSATA only (pass-thru) Dual Drive Enclosure ($59.99) with two 1TB Western Digital Caviar Blacks (SATA II, 7200rpm, 32MB cache, drive firmware 05.00K05)
• Maxpower eSATA 6G PCIe card ($59.99)
• Dynex (Sil3132 based) 2-port eSATA II card (appx $20 - also a 1x card)

The 3132 card used driver v1.1.11u, released Oct. 2009. (Again, 32-bit drivers only.) No S.M.A.R.T. support with my 3132 card, although there was using the NewerTech card.

Checksum/File Integrity Tests: Just for my peace of mind, I verified (10 times) that an appx 500MB .DMG file (the 10.6.2 combo updater download) passed a checksum test after copying to the eSATA hard drives in the OWC enclosure - both cards passed as they should. (But I've seen cases where this test failed with some card/ext drives (i.e. a natively supported JMB360 eSATA Expresscard in my MBP w/10.6.2 and several eSATA HD docks for instance) - even though no BBOD/freezes happened as I'd seen with earlier SL tests. I'm not alone in seeing that problem...)

Of course I also did sleep/wake tests - no problems were seen. (Normally I rarely sleep the Mac Pro, although I do with the iMac that is used for daily web work/email, etc.)

Benchmark Info:
I'd recently bought Drive Genius 2.2.1 and used its "BenchTest" for the results below. (BTW - Prosoft officially does not support RAID volumes with this software - although Benchtest worked for 32-Bit boots in Snow Leopard with the RAID volume - however it would not complete the benchmarks (single drive or raid) when run from 64-bit 10.6.2 boots. I'll try again once 10.6.3 is released.) Also I saw several cases where BenchTests' listed 'avg' rates were higher than the max rate for the run. (The small text max/min/avg they include under the graphs.) Here's an example (clip from a screenshot) - incorrect avg example (I sent the Drive Genius programmer a FYI on that as well - he later confirmed the "Avg" bug, but said the graphed info was accurate. This should be fixed in the next update. I asked to confirm there would be a free update to DG 2.x owners, rather than just being part of a major version (i.e. Drive Genius 3) update.) The NewerTech 6G card was supported in 64-Bit Snow Leopard however, unlike the 3132 card. (And although I'm not a big fan of Xbench, its disk benchmark completed ok in 64-bit SL with the NT 6G card.) Overall the weekend I plan to run some Kona benchmarks on it. All benchmarks were run using the OWC eSATA only (pass-thru) Dual Drive Enclosure and again, drives used were 1TB WD Caviar Blacks (SATA II, 7200rpm, 32MB cache).

Single Drive Results: (Empty drives, std HFS journaled format)

I noticed BenchTest's sustained read rates (consistently) had frequent peaks/valleys although no other apps were running. (I need to investigate that further and plan to run some Kona benchmark tests to see what they show.)

RAID 0 (2 drive stripe) Tests: (for stripe size I selected 64kb, the midpoint option. BT and Wireless off, no other apps running, drives were empty for all tests.)

Short notes on Windows 7 (bootcamp) use:
Since one of the HDs in the Mac Pro already had Bootcamp/Windows 7 Pro, I used it in Windows also although only for a short time so far. (On first boot windows recognizes the card change and pops up the usual "installing..." prompt - read to use in a few seconds. And every boot to windows/bootcamp I see a DOS message on Marvell controller initializing - w/info on any connected/powered up eSATA HD.) At the time I had an eSATA HD Dock connected to the card with a 2.5in Toshiba 500GB (5400rpm) Notebook Hard drive in the dock. I use that HD (NTFS formatted) for media files (movies, photos, music, etc.) that I play via the eSATA port on an Asus O!Play Air. (Unlike the WD Live, the O!Play wouldn't recognize connected HFS drives.) Anyway I copied several 1GB+ video files from the 2nd partition (a FAT32 volume I label "Shared" as it's R/W from MacOS and Windows) of an internal 7200rpm (3.5in) HD to the eSATA dock's notebook HD - windows exploder info showed copy rates from 80-106MB/sec (maybe due to system write cache, as that seemed high for a notebook HD like this - later large file copies showed from a consistent 80-88MB/sec (for complete duration of a 1.6GB file) to as low as 40-50MB/sec for 2.7GB file. Another 2GB file copy showed consistent 80MB/sec rates. The 500GB notebook drive is appx 1/2 full now). Next time I do this I'm going to use a stopwatch (and divide filesize/time to get an avg real-world rate). But regardless, I'm very pleased with the card's performance I've seen so far.

Summary:
The above is from my first night of testing but I've been very pleased with the NewerTech 6G card. Again it's a perfect fit for me (not expensive, good performance, PnP/no drivers required, S.M.A.R.T. support) and although I currently rarely boot to 64-bit SL (that may change in the future), the fact it's natively supported is still a plus. And maybe later this year I'll have some SATA 6 hard drives to try with it - unlike my previous card this one has more headroom for faster drives in the future. If like me, you don't need PM support and can't really justify higher-dollar drive arrays and controllers, this card may be just the ticket for you as well.

I normally reserve final judgement on anything until longer term use but here's my
summary after a day of using it:

Pros:
• First shipping SATA 6 card for Macs (to my knowledge)
• Plug-n-Play/Natively supported in OS X 10.5/10.6 including 64bit Snow Leopard (and windows)
• Good Performance/bang for the buck
• Affordable
• S.M.A.R.T. support (w/SATA-only case used, not checked with other/bridge board based cases)

Cons:
• No Port Multiplier Support
• Not Bootable (although ditto for many Mac SATA cards)

If I see any surprises in longer term use I'll update this page. So far though this card looks to be a great value for my needs. (I have no plans to go back to my previous card...)
-Mike