Here is a video of my 10 year running a Honda CRF250 against the opens at ECS earlier this year. Honda has had a bigger vaules installed and runs on pumped gas. Everything else is bone stock. He also weight 420 where the opens weight is 450. You can see the 250 doesnt pull down the straights with the 500s but can make up ground in the turns. We ran this motor while our JGR was getting repaired. Yes the JGR is a huge difference in power.
We have ran against 125 and 250 2 strokes and it seems the 4 strokes run much better. Thats just what we have seen here in Illinois. Yes ECS needs to get a 250 class started. At the nationals there was 31 Box Stocks and a lot of these kids will need and could move up to something faster with more power.
https://www.youtube.com/watch?v=AkZuL1llyto