Personally, if I'm going to spend that much on an enclosure I may as well buy an external hard drive off the shelf. I don't need eSata because I wouldn't be able to utilise that at uni, even though it would be nice at home. Basically, while the 2.5" portables aren't going to be as fast, they are going to be more convenient. As for the advantage, if I lose either than it is pretty much just as bad as losing the entire external drive.
Thanks for the input though.