You're right about the manual to some extend, we never had gearing recommendations in our speedo manuals but in the case of the SPX StockSpec we could (or should) have mentioned it more clear that the high profiles require a much smaller pinion.
Will make sure this get's improved with a possible manual update or future products.
As for the damage of other motors, when used with high speedo profiles on SPX StockSpec, I don't really now why they get damaged so much easier then our own X11 StockSpec as mechanical timing in the different motors seems very similar. Possibly our wire is of higher grade as a possible reason.
We were not aware of possible motor damage during development of the SPX StockSpec, we tested it most with our X11 StockSpec motors of course but we also ran with SP and GM motors during development and didn't experience any motor failures.
@billy: The SXX doesn't have those extreme profiles as the SPX StockSpec, but the SXX's profiles 9 and 10 are for sure also suited very well for stock brushless motors.
As for the heatsink, I do think you get away without it in all the classes you mention except for Truck Mod.