If you’re thinking of jumping ship to support your club in getting new folks into karting that’s a great thing. But…. The LO206 will be quite a bit slower so unless you get a bunch of other Yamaha drivers to switch you might get bored either running by yourself or smoking a bunch of newbies. If it were me I’d seriously think about getting another kart like the one on my website for LO206. That way you could run both classes, let a friend race your extra kart, or sell it to somebody just starting out. If your club wants to get people to switch over from Yamaha World Formula would be a much better choice since lap times are comparable and you still get the reliability of 4 stroke.
BTW, I don’t consider moving a seat strut over an inch a “modification” more of an adjustment….