Jack, we've been down this road and they simply DON'T come out. It's great that you are willing to sail this way but the bottom line is most aren't.
Heck their is a perception within the F18 fleet that the older designs are not on par with the newer boats and yes I do think this perception is impacting attendance. Look at the number Tigers that sailed the 2005 NA champs and the 2008 NA champs.
The N6.0 guys are pretty much extinct and the H20 guys that are still getting it done I suspect are pretty hard core OD guys. The Fox although a pretty cool boat came and went before the glass could finish kicking off, and I think the handful that made it to the US are now gone or no longer sailed.
So, what the N20 guys are currently doing is the best option in my opinion and if a F20 class takes on a life of it's own based on that then great.
"Do or do not. There is no try." - Yoda "Excuses are the tools of the weak and incompetent" - Two sista's I overheard in the hall "You don't have to be a brain surgeon to be a complete idiot, but it helps"
