The downwash felt by the parachutist is a function of mass of the aircraft divided by wingspan or rotorspan - it is not really much different whether fixed wing or helicopter. Even if helicopter is stationary it is not reallly any different from a moving helicopter, as the parachutist is initially moving at same horizontal speed of helicopter. I’ve jumped from C130, Chinook and C17 and the latter was by far the most violent, the Chinook the least.