Ayton is, already, a significantly better defender than KAT.
And yes, motor is a big concern, and KAT has a lot of questions about his motor and he has already shown he doesn't care about defense and many think he doesn't care about winning.
KAT is better than Ayton right now, I am not denying that, but KAT has serious warts himself and I don't think pairing Booker up with his buddies is a good idea.
I don't think a KAT Booker team has much of a ceiling. I would almost rather blow the whole thing up than cap ourselves out with a team that will, at best, fight for 7th or 8th seeds.
And back on the motor... Ayton's "motor" has been fine, he has been busting his butt on defense and on the glass. Where Ayton worries me is his settling for garbage long jumpers.