brushless motors are vastly more efficient and vastly more powerful, they also offer some very sophisticated mechanical timing features which can be read digitally using a motor analyzer to help you fine tune the readings across all 3 phases to help you optimize efficiency to power settings when shimming the rotor. I don't think this level of tuning is available for brushed motors, yeah maybe you can get some RPM readings, but I don't look at those numbers when I'm tuning my motors on the bench. I set timing based on current draw and check the phases to ensure optimal power/efficiency.