It's an interesting debate so I'll keep this running
Know of at least 2 S76 that CFIT into the ocean in the GOM
I don't know the details of these accidents. Do you think inflation of floats would have made any difference in these cases, given they were a CFIT?
The Aux Flotation systems are designed to keep the aircraft afloat in the event of a ditching (i.e. controlled alighting on the water) long enough for the occupants to get out and board the liferafts. For any other events e.g. CFIT at speed, then all bets are off.
I have no reason to doubt
Really? I'm surprised you would say that. I have gone through my career doubting and asking why! The fact that the AW139 is the only offshore helicopter that doesn't have a float arming speed coupled with the lack of OEM in-flight testing makes me doubt!
I'm not saying my doubt is founded on facts, it as actually based on the lack of facts!