There are issues with USB from a compatibility standpoint. I think its mainly a factor of the ubiquity of it, there are SO many poor controller chips out there, even when you buy seemingly reputable hubs/drive cases. Its hard to find a good one sometimes. I did, however, stumble upon a gem early on, it was a 3.5" usb drive case from BestBuy which has since been discontinued(because it was good). Never in 15 years has any of the half dozen ones i got dropped from thier system. This is more than i could say about alot of pricey stuff on amazon sadly. Its typically manifested as a random loss in connectivity to the system.

Similarly, heres a very low power writeup I did for using 2.5" drives with a dedicated power hub/splitter. http://www.jofla.net/?p=00000106#00000106 This will still have issues if the mains lines sag (a pole goes down somewhere), but you can fix it with a reboot remotely. Other than that it works great.

This was/is definitely a labor of love, primarily as I've come from a time when all you could get for a server were huge boxes idling at 50 watts, so i felt guilty of all the power I used to consume.