I generally hold ex-bush pilots in high regards for their stick and rudder skills. I see no reason why they wouldn't be successful in a complex aircraft like a 139, subject to a thorough pilot initial on type. In the simulator during recurrent checks, when the automation stuff starts breaking down, I find the guys with solid background in stick and rudder flying usually manage a bit better (on average) than pilots who have been brought up mostly pushing buttons in helicopters.