See, I experienced the same thing. When I raced against guys that have OS 12TZ 3 port motors, they were able to hang with my Mugen X12 on the straight. The straightaway at my local track measures 150 ft. Pretty damn long...and if the OS 12TZ can hang with my X12, that's pretty damn impressive to me. Only engine I've seen that can smoke my X12, is an RB v15.
Still deciding on what to get...but I'm definitely leaning towards the RB V12 5 port. Since my local track hosts club races, they allow any motor to run.