4s vs 5s on Neu 1512 1.5D and 1515 1.5D?

[Ryu James]

Does anyone have any experience running a 5 cell LIPO on a 1512 or 1515 1.5D motor? i have both these motors running on a 4s 25c 5000mah battery and they perform great. but i am speed addict and i know these motors are capable of 60k rpm. currently the 1515 runs at about 38k rpm and the 1512 at just over 40k rpm i think. the 5 cell will take them up to the 50k-55k rpm range. i dont intend to use the 5 cell often, just for bashing and having fun with some speed but i dont want to waste $250 on a 5s battery if it wont add alot of speed over the 4s and if it will damage my motor. anyone tried this before? and with what results?