All interesting posts, and most to the same conclusion.....it sinks quickly and more than likely inverted. One thing I havent seen posted here is based on some rules I read somewhere. They mentioned something like "within autorotational distance from land" OR mandatory floats for work out of the above requirement.
As to floats working well, if all else goes well. Gary Manion can take credit for landing a B206 in the Ocean off St Croix last year.
www.aircenterhelicopters.com A rather textbook autorotation after an engine failure. Floats worked and the aircraft was in fact towed to shore and is again flying. Time to give the man a hats off for good piloting.
On the no float list we can also say that recently a Pilot?? placed an Enstrom into Hartebeesport dam area of South Africa (pprune post earlier) without floats. Viewed Damage indicates to me of high speed, low level with what we call "inability to judge height above water." That coupled with girlfriend on board indicates, at least to me, of a Testosterone problem. It did not float.