eSATA and SATA in general
I wanted to chime in here as the potential looms for external drive connections.
The SATA spec, itself, is pretty feeble insofar as the number of connect/disconnects the spec defines as lifetime.
The eSATA spec is more robust, but is still defined (if i recall) as a total of 200 connection cycles. Of course, if you are careful you can likely easily exceed this, but...
All you need to do is look at the physical connection to realize it is not very solid, and most connections can be easily wiggled even when new. Compare it to a SCSI connection, there is no comparison. Heck, even an IDE connection is way more secure feeling.
I have recently been through this as I wired a satellite receiver to utilize an external eSATA and found the connection was causing huge issues as it wrote HD content to the external disk. I finally changed the physical connection to one of the (rarely used) snap-down SATA connections to prevent the cable from moving, etc.
Your mileage may vary. I think there is lack of wide-spread use of external SATA or eSATA and frequent, or hurried, or regular connection/disconnection which will lead to some unexpected pain. ;-)