Personally,I agree with you on the 26mm tires. The funny thing is that many people wanted changes to RCGT for that very reason. "Oh, the x-patterns wear badly. Oh, the x-patterns are too expensive. Oh, we shouldn't have more than 1 compound available, blah, blah, blah. I think you remember that thread. The "orphan" motor thing may not mean much and I agree. The fact is that the 21.5 is viable in some other classes but who really cares. VTA uses the 25.5 and it's basically unique to that class. The 21.5 is just a better answer IF we want to use tires that really aren't meant for 17.5 speeds, IF we want to attract new drivers, IF we want to provide existing drivers ANOTHER form of racing without the headaches of TC.
Here's another consideration. Just like VTA....try it. Next year when 17.5 ROAR sportsman rules are supposed to change and eliminate programmable esc's.....then consider upping to 17.5 IF AND ONLY IF enough people involved in the class want to.

Man, I told myself I wouldn't get to involved with this thread. It's not my call. The bottom line is that it appears GT groups will adopt whatever rules they want and I think most all of them will continue on that path. The genie is already out of the bottle....few to many will care to change 1 way or the other. Rob, you got your work cut out for you.