currently, the only 500's on the 500T grid that cannot race in 450 superbike are the SV500's and Kevin's Gibson.
The Gibson is a true formula bike, so it really shouldn't be eligible for 450 superbike.
The EX500's are actually legal for not just 450 superbike, but also 450 production (as long as they are not modified outside of the production rules)
I feel that the SV500's are consistent with the rules of 450 superbike, but the AFM rule book says otherwise.
As for how well 500 twins do in Formula IV or 450 Superbike - the fast guys on the 450's are also fast in Formula IV (there have been winners on 450's in past races, its not always an SV!). So, we'll still be getting smoked - your finishing position just looks better because there are fewer entries in superbike than F-IV
Even if I could run 450 superbike, I would still run Formula IV - while a 500T is at a disadvantage on that grid due to the displacement of the other bikes, its great practice for how to deal with traffic on faster machines and a good way to improve riding skills by having to chase faster bikes (and I could certainly benifit from that...)
hmm, maybe we should enter the 500's in 600 superbike afterall, it might make us feel like we're competitive in F-IV...
I'm not sure we need to petition the board to give us a second 500 twins class - we just need a few tweaks to the AFM rules (and in fairness to how the current rules read, the SV500 to my knowledge is exclusively a very recent AFM phenomena, so the rule book wasn't written with it in mind)