Hmm, all good stuff to know, thanks everyone!
I'll mull it over a bit longer. I really do like the flexibility of the portable version...I'll have to weigh it against my personal weakness of not backing up as often as I should (I really try but I'm nowhere near as regular as I should be
) and the risk of forgetting the USB stick (I think I have a keychain one though, so that would solve that problem).