Several months ago, I saw a Syba branded eSATA PCI-e card online for about $7. (I don't remember exactly which site, but these cards can be easily found online for about the same price.) After I confirmed that it contained a JMB360 controller, I made the purchase. I suspected that it would work with OS X without additional drivers based on what I'd read about JMB360-based Express cards for MacBook Pros. When it arrived, I found, to my dismay, that it had one of those half height PCI-e cage brackets. So, I had to do a bit of hacksaw and Dremel work to extend it to full heigh before it would fit in my Mac Pro. This also explains why I had it sitting in its box for several months before I installed it... Well, I recently had to copy a bunch of stuff off of a failing hard drive that was in my Mac Pro. Since all the internal bays were used, I first tried doing the copy with an external USB based dock. Once it started, Finder estimated 18 hours to finish. Screw that! I took out my eSATA to SATA cable and jury rigged some power to the new drive and it popped up on my desktop. I proceeded to do the copy and this time, Finder estimated 2 hours to finish! I've only used it that one time and probably won't use it all too often, but it's a fantastic option to have. At $7, it's hard to beat. I know that my Mac Pro has two unused SATA ports that I can route to the back, but I do use one of those ports for an internal optical drive and, from what I've read, they do not support hot plugging which this card does. Why this instead of SIL3132 based cards (which can also be found at extremely low prices)? Built-in OS X support. No need for drivers! To those who intend do something similar, don't make the mistake that I did... Find a card with a full height PCI-e cage bracket.