17.5 would be a lot easier on guys running rcgt or tc. I think using 17.5 will bring more ppl to the event. If you look at any club racing, 17.5 is the largest or 2nd largest class. In different variables. It just seems that 21.5 & 25
5 isn't leaving enough gap between the 2 motors. Non boosted 17.5 is a good step up in speed to vta 25.5


That's just my opinion