I have to say, I have had none of these experiences with any of the five 2.5" drive enclosures, or drives that I have/use. Sony VAIO enclosure, Maxtor 2.5" enclosure, IOgear enclosure, and two simpletech enclosures.

None have failed, and none require additional power (although, I have heard that some require a second power in, that is usually based on either low powered ethernet ports, or older v1.0 USB. That isn't really an enclosure issue, more a desktop or laptop computer issue - the PORT not being powered enough.

I've not had such a problem though, with mac powerbooks, macbooks, IBM thinkpads from six years ago and newer, but it COULD happen.

just another data point. The real only downside I see, is that the $ for MB is a lower yield than larger 3.5" drives, but if portability is key, and size, and the gross capacity is not an issue, nor absolute cost/benefit, then the 2.5" inclosures fit a nice bill