I havent had a replacement transmission but I have broke stock tranny parts after a fulls shep stage 3+ build and had to tear the car back down to fix them. (800+whp pushing the car hard on a road course)
that said, i would do it all again in a heartbeat.
absolutely love my gtr
2015 Alpha16 GTR -17xx WHP, 14xx WTQ, 213 HALF MILE
2010 Nissan GTR,TopSpeed Motorsports 4.4 Liter Alpha12+
Motec, JRZs, HREs, Alcon SuperKit, Carbon Errything,etc
8.97@164 - 206.99 half mile - 1401whp 1095tq Road Race Prepped Monster Killed on Hellbender 28