Ha! Thanks for all the lofty theories but I've been out working in the yard all morning!
I'm still uncertain about the tire thing. There are good arguments on all sides. I still kind of lean toward the "any rubber tire on any realistic rim" side.
@billdapart: The whole timing thing can get pretty complicated and it would be way easier to fill you in in person rather than write a long treatise here. In short, timing is a completely separate thing from throttle/brake profiles and current control. Also, just because an ESC has fixed or non-adjustable timing doesn't mean that it's zero timing. I think the issue with the Cirtix as it stands is that, although it's not user-adjustable, there is a "canned" timing advance scheme in the firmware. Therefore, it's not on an even playing field with true zero-timing ESCs like the GTB, Havoc, LRP AI, etc.
The silver can class is a stop-gap. A bunch of racers unhappy with ESC war RCGT but sick of waiting for a solution (understandably so) chose to go the cheap and easy route in the mean time and run silver cans. I see it as a temporary move. If you think the speed disparities are big in 17.5 between ESCs, you ain't seen nothin' until you see a juiced (but still technically legal) silver can blow by a regular one on the straight. Even out of the box there is a large variation from motor to motor. I'm confident that once the new RCGT rules package stabilizes that everyone will come back to the class.