i have the same issues as you do.
frankly, i have a 15" hp laptop and crash constantly due to the single-fan design that overheat everyday.
i actually stop by an apple store to take a look of the both, if you do stuff with the 15" laptop for more than a year 13" is no good for you, but than it comes down the price. 13" only cost 1099 for me as a student and 15" cost 1699...

anyway i will go for the 15 and i think you should do the same.
ill wait til the BTS time to buy