Your buddy is an idiot
more power means the motor will have an easier time making it's job easier so why would you need a new motor?
If the spring was significantly more powerful you might want to consider a motor or battery upgrade or both
with the 9.6 the firerate will increase and some will say that ur internals will wear out faster which is where the shimming and spring guide come in
google version 3 spring guide etc and make your decision