Jim, your navy memories are fading!
Having been a 'waterbird' instructor for my sins during my Canadian exchange, I can guarantee that anything over state 2 (ish) is going to cause severe stability problems to big helos, even those designed to ditch (S61 etc).
Smaller ones would not fare as well, I would suggest. It is true, flot bags are only there for one reason, to present the crew with adequate assistance to get out immediately after ditching.
The flot bags do NOT cater for:
Swell - blades striking wave crests.
Ingress of water into the mainframe - doubling the weight of the helo and thus exacerbating the orientation of the cabin.
The biggest problem for (most) helos is their tendency to tip over due to their weight distribution. This might be in the shape of a roll left or right, or a nose dive!
Either way, UNLESS you are sitting on a mill pond, I wouldnt saty in side the cabin for longer than necessary.
Dunker training is a MUST if you are a frequent 'feet-wet' flyer.