300R is a incredible motor. I want one, will be worth the wait for sure. They are proving not only faster but quicker than DBR (ecu tune/light flywheel) 300xs. The stock 300xs was not even close.
Benefits I know with my limited exposure:
1. R makes power all the way to 6400...power dosent start dropping off at 6,000 Rpms
2. R allows you to run on limiter without going into guardian (safer)
3 auto shifting is butter smooth
4. Sounds great
5. Getting power to the water is no longer an issue most seems to have unlocked and found how to make traditional props work now
Basically you will love the motor.