To me the M5 just fits my personality better. I hated the fact that everyone wanted to race me in the 930. Most people don't know what an M5 is.
As far as power i would say the power to weight ratio is the same. The turbo involved less shifting due to the 4 speed. It should put you back in your seat when the turbo spools up.
how does the M5 compare to the 930? I just aquired the 930 from my father, but it's not healthy....so naturally the M5 feels so much faster. I remember the 930 being pretty fast as a kid tho. Have any pictures of the M5 and your old 930?