I'm sure Adrian is beating his head against the wall somewhere becaus he already said this.
Just because the lap times were the same doesn't mean there isn't a huge difference in driving. A 13.5 has a heck of alot more rip when you get on the throtle compared to a 17.5.
As for buying a brushless system just to have it out dated by rules does suck... Although we all jumped into the brushless game wayyyyy before ROAR even thought about changing the rules for it. I'm not happy that I will have to replace my 13.5 with a 17.5, but its the way it has to be. 13.5 is way to much for a "stock class"