Had been running a B6 then B6.1D, sold them and bought a Rb7, while I was waiting for that to arrive I bought a 2nd hand Rb6.6, put all the plastic rb7 parts on it and have run that twice on a medium/low grip dusty predominantly 8th scale track, Thing is miles better than the AE to me, can't wait to build the 7 with 4gear lay down and try it indoors, So far the 6.6/7 seems quick, stable and responsive to setup changes