Helicomparator:
The Super Puma Mk 2 with 4 axis autopilot had a Vmini off 40 KIAS. Did a familiarization flight test when I was with Transport Canada to verify - set 40 KIAS in fully coupled mode.
Watched the airspeed needle drop to somewhere between 40 and the next slower (unlabeled!) line and stay there for several minutes. Never did get back to 40 KIAS. French test pilot agreed it wasn't very good. The limit for Canadian registered versions was set at 50 KIAS (which it held consistently), and resulted in several years of phone calls about 'Why is ours different than the French version?'
I doubt that there is enough dynamic pressure at 30 KIAS to work reliably.