In the world of Airliners, we are told to never use a circuit breaker, as a "Switch", as part of a normal or everyday procedure.
Bad for the circuit breaker over time usually, and I know in the Big Jets, the FAA frowns at this practice.
Using the Clutch Circuit Breaker to stop a Run Away Clutch in a Robbie, is an approved Robinson abnormal
procedure and part of the POH checklist.
Using the Clutch Circuit Breaker to modulate the belts during start up, would probably get more than a scolding from the FAA, Robinson, and your Insurance people, if you created an electrical issue or other, that ultimately took the aircraft out of the sky, at a later time!
My several years of flying my Beta II at 5,893msl elevations in very cold weather, taught me to really finesse the throttle on the early stages of the engine start sequence, and it worked well for me.
This incorporated a usually top notch battery, low time engine, and belts of average age and time in service!
Never really an issue, just a little extra skill that a person in a cold weather environment, needs to develop.
Of course each machine seems to be different than the next one too!Disclaimer:
I'm not a technical guy (No A&P or IA license), but I have been flying for 40+ years !
Hopefully as someone said, maybe a tech. guy will show up here soon, and give some better guidance than mine?
Beta II, N222JA
Ocala, FL (Formerly Denver, CO)