Bizarre limitations you have in the Seahawk and 332. Maybe just a feature of that helicopter but nothing like anything else I've flown. Most blades run hot, up to plus 6C at the tips, so normally nobody worries much about ice until down to about -4. Even then, as Shy Torque puts it, all we ever watched was the torque - icing up meant the torque increased. And it practically never happened, otherwise you wouldn't have a helicopter industry in Canada. Even those of us that went looking for ice would take off day after night in +2C drizzle and climb, sleet at 1000' snow at 2000' dryer snow at 4000'. The 212 and 222 could carry a whack of ice, 412 and 76 not so much, but it was a rare event anyway. Night IFR slinging in the Arctic in the winter - sometimes -30, sometimes -20, if it got warm then -10.
Icing tests just might be some kind of sick joke. "Yep, we flew through a cloud at -1 and didn't pick up ice so we know the anti-icing system works". Chances are that if you tried it for ten years without anti-ice you'd never have picked any up anyway. Watch an operator in Canada like Helijet with their S76 flogging around in moisture below freezing all day every day with 12 passengers in the back, or Cougar and CHC doing the same off the east coast. They know more about ice that anyone that turns tail at +5 (no offense, I know you are simply complying with an RFM limitation).
BTW, yes I have picked up ice on a few occasions. Very few, and in very specific conditions. And no it didn't stop me from flying into a cold cloud the next time.
malabo