A couple of weeks ago, with the announcement of the new MBAs, I decided to test the waters on bay for my mid-2010 15", hi res, 500 gb 7200 rpm i5 machine, figuring I'd sell that and get a 13" MBA instead. When I didn't get what I was asking, I decided to take a different approach. I've just swapped out both the HD and the SuperDrive for two OWC 60 gb ssds set up in a striped RAID array. All I've really given up is form factor--and even the MBP 15 is easier to travel with than my old think pad, with its crazy bulky 9 cell battery that still only lasts 3 hours with wifi on and massive power brick--and I've gained quite a bit of flexibility over the Air. If I really want to travel light, there's always the iPad. I highly recommend this approach, which might be even more attractive on a 13" MBP than a 15 (though then you're losing resolution).