I have a bit of knowledge on brushless motors, because I have been into R/C/ planes/ cars for over 10 years...it is true that there are certain brushless motors that have better efficiency then others , but I have found that in the R/C world... a brushless NAME brand MOTOR that may cost 2-3 times as much as a brushless off brand motor { with all other specs being simliar ** is usually not worth that extra cost because the performance factors do not merrit that extra cost for those of us who are just R/C hobbyists...Now, if one was a R/C proffesional, who attended races or competitions, then thats a different story.

I think what im trying to say, is that generally speaking , a brushless hub motor is not gonna be the mian component within these bike kits, that fails first...because these brushless motors are inhereintly efficient , and do not have alot of moving parts/ brushes/ contact points to wear out or break....

Now, if someone buys a brushless hub motor rated at 250 watts, when they really need one rated at 800 watts , then overstressing the brushless motor will mean more possibility of failure ..but thats not a fault of the brushless motor..it is a fault of the user not buying the proper equipment for their needs.