I don't know that the Mixing of the two classes would ever be possible with racing.
You could never keep both sides of the fence happy. As soon as one wins, thats why. their technology of choice is faster.
I don't think the intention is to mix them. I think the intention is offer racers slower BL motors so they can start using them.
I'll agree that under some conditions, the BL 13.5 is faster then some stock motors. But I won't ever agree always. A stock motor in the right hands is very fast. We're trying to offer that out of the box.
Someone email me or post, what they are doing to these motors and I'll glady try it out myself so we can see what's happening.
We can run ESC's with BL motors through a dyno we have and get hard numbers. I have load testers and can repeat testing again and again under the same loads. I just would like to know what everyone is "doing" to these things. I can see bearing upgrades possibly helping, but the timing thing is a none issue, what ever you gain, you'll loose from someplace else. It's physics.