My last motor was the sc4x 4.5. Great motor.
Replaced with a tenshock 411 4600kv motor and its in a whole other leauge. A lot more bottom end a little more top end. Both motors with a 13t pinion.
Runs cooler.
I thought the sc4x was a fast motor till I ran the 550 can 4 pole... I was impressed.

I have not run the pro4, I'm sure its a great motor but it costs 30% more and it's a 540 can. My $ went to the German motor.