The mption in a hele in turbuelnce is rather different from that of a small plane. The helicopter hangs from under the rotor system and swings a bit like a pendulum. The rotor system damps and absorbs the motion more than a plane too.
However, people do get sick in heles.
Motion sickness is a rather personal thing, but I always feel it is the unepceted and irregular motion when a person is not getting a good view of the horizon and the outside world that really gets them going. In general the external view from a hele is pretty good, which may help reduce the chances.