Being an airwork mission, I think it would be hard to get pilots to wear life jackets when in the bush, considering "most" dams and water sources anre not much bigger than your rotor disk.
fair enough if your pulling out of a lake all day but i still think it will be a fair challenge to get pilots to wear life jackets.
read the report and yes it is interesting. buket size and lift capacity are critical, on a typical mission on a 206 with 1 hour fuel aboard, pilot and 410 litre bucket your only about 10 kg below external max weight.
anyway interesting article from the atsb!!
cheers