I picked up a Vantec3 enclosure for one of my spare WD5000AAKS drives (see My Computers for updates), and made sure that it was one of the versions that included eSATA support. I’ve dealt with USB enclosures for a long time, and the transfer speeds are just painful. I took a couple of benchmarks using HDTach – one with the drive connected via eSATA (on the left), the other using USB (on the right).
I think the numbers speak for themselves. Don’t let marketing fool you either. That “480Mbps” speed from USB2.0? There’s two problems with it – first, it’s Mbps, meaning megabits per second – not megabytes per second (divide by 8 to get MB/s), and secondly, it’s a theoretical maximum of the hardware. Because of the way that the USB protocol is coded, that 35MB/s is about as good as you’re going to get.
If you’re looking to get a hard drive enclosure, do yourself a favour and get one that can do both USB and eSATA. If ever you need to copy tens or hundreds of gigabytes of data, you’ll thank yourself.