the pwer valves on the big cheeta engines give the bike more low end. it is a valve that goes down into the exhaust port and it makes the exhaust port timing lower till you rev the bike up then the valve pulls back out of the port causeing the port timeing to raise and become a drag port in a way. the big cheeta would be better for trails but they are alot more expensive to build cause they use custom domes, reeds, intakes, and you have t have them ported, cases trenched pending on what stroke you go, and you have to cut the top case half cause most of the cheetas are big bores like 71-74mm
cubs are nice because they use all the stock bashee stuff.
If you are not building a drag bike why dont you just have a good builder port your stock jugs to fit your riding style.
FAST charges 350.00 for a dune port. you will have about 1500-2000 in a cub, and I am gonna guess at about 2000-3000 in building a big cheeta