Normally ESC wil not make that mutch off a difference.
If you use a hobbywing 21.5T you can't adjust timing.
If u use a speedpassion motor, you can add timing, use other sensor for more timing and other rotor. That makes more difference than the esc.
Overhere in Belgium for the nats, everybody has to use the same motor, with fixed timing, and stock rotor. Now there almost no differnce in speed.
Serpent, VBC racing, muchmore racing, skyrc, nosram,...
Driving a ERYX3.0