I don't think LRP made larger rotors to decrease the performance of their motors. I had 2 of their 1st gen and they were terrible, they needed something drastic to catch up with novak.
Just because the lrp is larger does not mean it is any stronger than the novaks smaller rotor.
Using a brushed motor as an example doesn't work. They did not increase the size of the motor to gain the extra torque. So they had to lose out somewhere else in the rev range.