In the B model with the PT6 and Fadec, we do not have to diddle with the trim switches, as the computer matches the chosen parameter for us.
And the choice is: Match Torque (to keep the input power to the gearbox balanced) or
Match T5.
No mention of N1 or fuel flow.
I can't see why you would attempt to match fuel flow. Even in a guzzler like the PT6 there is only a difference of 20 lb per hour at 75% Tq and 145 Kt.And the needle on the fuel flow gauge flickers more than 20lb anyway.