Eagle 86 said "Never had to really unlearn anything nor, in my experience, did any of the studs I taught to fly machines after they'd learnt on the uh1b or as350."
Probably because of the superb training you gave us, 86.
UNLEARN training? Urban myth. You step into a different helo, and the checks for that particular type slot into their respective brain cells, and away you go. Unless you are flying 5 different types in a day, not a problem. In one day, I strap on an S76, a UH-1H, and a B47 and back into the 76 and there is never any mental conflict with types or techniques or critical speeds or such.
Only time I almost made a mistake between types was going from a Chieftain to a Baron - cockpits almost identical, but the flaps and gear levers were interposed. Went to raise the flaps of the Baron after landing, and stopped when the feel of the round wheel-thing on the lever wasn't the same as the square thing on the flap lever. But that's planky stuff...