mitch-
If youre talking about ability to break cars, then yes, I am in the know.! lol
I have been running a spool since I got it without any pin problems with my "newer" kit.
However, out track is super low traction carpet (think negative traction almost!) So I have a diff on order as a couple of Shumacher's driver here have had better results with the diff on our track. BUt for the acerage track asphalt or carpet I believe the spol is the way to go.