With Back to My Mac, the size of the portable's "hard drive" becomes largely irrelevant. Well, unless you don't have .mac 🙂
True, however, not many of us are willing to pay for .mac. I know it is a bizarre human behaviour, and I'm no different. Paying $100 for a year to store data on the web? It sounds like a case for a Google solution!
Apple is not always right
Cinch