Bob, the Western NY Kart Club (formerly Batavia Kart Club) has a similar class structure where we have a combined stock Animal, KT-100, and World Formula class equalized by weight. I wish I could say we have better luck with it, but it hasn’t been as successful as we’d have liked. It does offer easy entry into the senior classes on the engine side – there’s a lot of Animal and Yamaha engines out there.
Honestly though the WF should be where it’s at for the experienced racer who isn’t into traveling to nationals and doesn’t want to spend a lot. They’re just as quick as Yamaha can out of the box, and they run forever with just oil changes and carb cleaning.