i have tried a few different fuels out there and byron 20/12 none of the motors liked it. i would get sputtering and always would overheat the engine or stall the engine( too rich). it was a hard fuel to tune for me, the one i currently use is sidwinder 20/12, i put it in and set the needles and havent touched them since.
if you want to go to a lower nitro content its just like breaking in the engine again, you need to do the procedure all over again.

good luck and i hope this helps you.