Well, you could save yourself from some loops by going with a less aggressive rear tire, a slower than normal turn throttle, or a heavier flywheel, that is usually after you tried everything you know to tame the beast.
Wonder what the wheelbase is, and swingarm length, compared to standard 4 stroke CR-500's. I know some pros spec longer wheelbase on their bikes, especially outdoor bikes, for stability and to tame the power.
I was never a fan of huge horsepower, even in 125 Expert, as wheelspin and traction offset the gain in pure HP. Even in starts, you still need traction besides pure horses. I hole shot a few VetExperts with a 125, and several with 250's, against the 500's of various makers in the class.
OTOH, I"ve never ridden anything more powerful than the 4 stroke YZ-