Last time I was in Norway in 2006 the CHC Norway engineers ( who had the training) ran the S-92 aircraft and probably the Puma to. They did both with rotor brake on and right up to fly position runs rotors turning.
They told me they went to Flight Safety ( S92) for training on running the aircraft and any emergencies they might encounter during a ground run.
I feel with the correct training there is no reason why the engineers can not run the aircraft. Is quite common practice in the fixed wing industry.
I agree makes the pilots and engineers both happy.