Had my havoc setup going last weekend and found it to be quite capable. My initial rollout was 62mm which seemed fine (which was fitting because the track had been shortened since I was last there). I thought 1s 13.5 would be too slow without boost (backup plan being putting the system in my 12th scale or Legends) but it really surprised me.
For some strange reason the ESC comes with throttle expo turned on by default
I thought this system was designed to go in pan cars...
Otherwise, quite happy with the product.