Thanks Eddie for taking the time. Still not ENTIRELY clear on some of it, but I think clear enough for "campaign stage".
As re: PT's...I have PT's in ALL my cars that are raced (two TC's that see limited use, two 1/12 cars that see the majority of use, and a 1/8 off-road buggy. That's five PT's, and I have a back-up in my radio case (with my spare receivers and servos) for a total of six. I just see them as part of the "equipment", just like batteries or a motor when I build a car. And it ain't like I'm "loaded" either and don't have other places to spend my money--I just see it as part of what's needed to compete. Then again, to your point I came at it from an on-road background, though not for the reasons (switching around) you suggest.
Scottrik