Nice work so far on the rules.
I would definitely recommend grandfathering the DM1 and extending a date on the dish wheels (two years from yesterday sounds good).
What are the thoughts on engines for the spec class? In our locale and others, $200 pops up as a very common limit. This is not based on a one-time out-of-the-alley price tag but rather on general availability at this price. Or do you think you'll just stick to RTR engines (this has its owl perils).