The problem is, those first few seconds, or even second are incredibly valuable. It doesn't take long for a rush across the arena to happen and most spinner impacts occur when the weapon has relatively low RPM. The big impacts are few and far between and generally due to chance more than anything else.

Thermal mass of the motor is another issue. I have no concerns about an etek burning out (my wiring and batteries are more likely to) but I just don't have the same confidence with brushless kit.