Hey you guys, the difference between a monster and an SS on track? Sod all I would say!
Speaking as someone who regularly gets whupped by 250's, supermotos, singles, even 125's, I can tell you that the rider is way way more important than the bike.
Personally, if I could afford to do it, I would get an SS just because I'm more comfortable on that type of bike. I think it would be a real shame to exclude SS's and 620's too. Like Lizzy says, that'll just limit how many people might want to do it. You need to get 25 entries remember, so let everyone in, if it turns out that 620 SS's and Multi's are ruling the roost, then change the rules next year to reflect that, because by then you'll have everyone hooked!
In these days of dwindling club race Ducatis it would be so cool to see this take off, I for one wish I could afford it, it would be a great way to build my experience.
I suppose what I'm trying to get across is this, don't spoil the pudding arguing about the details just now, give it a taste first!