I looked into buying one. No real rocket science involved. Only decided against it because other parties were involved in the transportation of the hard drives and without an enclosure, I just couldn't trust damage to the circuit board.
picked one up from http://www.pccanada.com/viewitem.asp?id=7552 a couple weeks ago and like it as i can swap out multiple small drives i have easily. makes multiple backups easy to deal with!
Only decided against it because other parties were involved in the transportation of the hard drives and without an enclosure, I just couldn't trust damage to the circuit board. Just my opinion.
I totally agree, unless I was the only one handling the hard drive I could not trust anyone else to possibly damage the drive by spilling something on the drive or somehow shorting out the drive via the exposed circuit board while in operation. It is handy to be able to hot swap drives this way but I think if you want to how swap drives buy the 5.25 drive bay enclosures such as this which mounts in one of your drive bays:
This might cost more but atleast there is an enclosure protecting the hard drive.