I'm probably not a typical user, but over and over again I find that while browsing on the iPad that I want to comment at length on something I read, which I hate doing on the touch keyboard. I also tend to browse the web with a bunch of tabs open and switch around quickly and this also isn't so pleasant on the iPad. Something like the 11" MBA with Ableton Live, Adobe CS, XCode, Terminal, Chrome, and Transmit could be all the computer I need and would be no trouble to port around.

At this point the only thing I strongly prefer to do on the iPad is read ebooks. I wonder how many people there are like me that love the portability and convenience of a tablet but would be happy to put up with a slightly larger device if it meant they could do real work with it as well.