Keep in mind that the 13 doesn't have the expension bay, nor the input modules. I really do want those 2 features, so U am strongly considering the 16", even if it is a little big for my taste.
Also, I would rather take a r5 and have increased battery life (I bet the r7 are binned for higher perf and have higher leakage), but they only offered the bigger battery with the r7, last time I looked.
16" is definitely big (I have a desktop and docking station anyway), so I've refrained from ordering for now, hile I decide :|