You are going to get a LOT of opinions on this subject because people have personal preferences that they like. Dyno K and Cyclone Heavy are both good oils, as all of the guys above, I would recommend AGAINST mixing the oils, and as Jimbo said, both manufacturers would probably recommend the same.
I have not used the Amsoil 4t oil yet, but I hear it has good reviews. Dyno K & Cyclone are good, I like Thor lite or heavy, I have also had good luck with FHS Hurricane medium. Honestly, it's hard to get a "bad" oil these days. Change it often, don't overheat your engine, and keep a clean air filter on it and worry about racing. You are not going to win a race just by changing oils.