I didn't have paddle shifters on my M45, although Dean (DeanM45) added them himself - I changed gears with the center console shifter.
I sometimes forget that I have them in my M37, muscle memory seems to kick in and I go to the shifter instead of the paddles....BUT they're nice to have when you have both hands on the steering wheel and don't want to move them ANNND they look cool!!
Shifts seem pretty good but the only cars I can compare it to that have the manumatic option were my non-sport 2000 Acura TL (seems a little less crisp vs Acura) and my wife's 2012 Dodge Durango (M seems better) Curious if upgrading with a TransGo might solve the shifting delay??
Seems like you could the parts used for cheaper than $500, wondering if the G37 paddles are compatible with the M, seems like some guy on the myg37.com classifieds is regularly selling theirs - might be worth looking into