I've had externals on a couple of occasions. The drives themselves seem okay, if a little slow due to the interfaces I've had for them, but the enclosures have developed problems that killed them. I think the ventilation on one of them wasn't designed too well, and I can't remember what broke too easily on the other.
I haven't needed to transport that much data anywhere for a while, but I just use internal drives with a hard drive dock (I have
this one right now) if the need arises. It's not pretty, and it's not quiet, but it serves my purposes better than the normal external setup.
If you're going to be transporting it around, I'd look at getting something more rugged than the cheapos, but I'm really not sure what the options are for that. Probably more than you want to spend.
