Originally Posted by JumpySticks
I don't see any warning in the manual about running at partial throttle. I expect that it's ok so long as you are not restricting the airflow.
A warning appears in the Radian manual (same power system):
Note: The power system installed in the Radian is
designed for climbing use in bursts (50% operating
time or less). It is not intended to run full throttle for
long periods of time. Not following this direction may
result in reduced life of the power system.
They probably didn't mention it in the RP manual because it was aimed at the more experienced gilder pilot. If it's fussy about full throttle, then you can bet your life it's more fussy about lower settings and the heat they produce.