I'm not going to just say this once. We should not, repeat, NOT try to gain an advantage over the four-strokes by imposing rules and limits to keep them down. If sound limits are imposed, it should purely be a noise pollution issue. The second you start talking about using a rule like that to slow down your competition, you've entered into the playing field of doing exactly what the Big Four have been doing all along. The philosophical ideal is a level playing field. You get X displacement, you have one cylinder, you burn gasoline, and that's all that needs to be said. That means that the competition is about the riders, and the bikes, and not about who can wave their dick around at the AMA and get them to dole out some favors.
As for changing the rules to 250 vs 350F, I do think that would be a step in the right direction, however, I don't think it's something we should pursue. The Big Four don't make 350Fs, and have warehouses full of 450Fs that they need to move, and now we're going to tell them that the "little guy" KTM's 350F thing is now the golden standard? They'd shut that proposal down so fast it'd make Clint Eastwood open his eyes (for the first time in 40 years) with surprise. I think 300 vs 450F works better, because it's easier to take a 250 two-stroke and make it a 300, than it is to take ten million 450Fs and make them into 350Fs.