I've been racing my Pro4's for the past couple of years now.
One in our Trans Am class (6 cell Nimh Silver Can) and in our 27t brushed/17.5 brushless class and both cars have been running very well!
I have some spares but don't think I will really need to worry to much as we use Road Rails for our track although 2 sides of the track are asphalt curbing! So as long as you don't go wide your usually o.k.
The only issue I had with my Hacker 17.5 brushless powered Pro4 is having to pick up pinions from 52-59 tooth!!!!
