rotormad,
You can use a f/w headset in helis if you get a converter bit to stick on the end of it. The only problem is there are two different types. I got one off ebay for about £12, only it turned out to be the wrong one; works for a few R22s in this country, but not most of them. I can't remember any details, except you want to get one with a silver coloured bit on the end, not the gold coloured bit, which is what I got.
I don't know if this makes much sense, but I'm sure someone who knows more about it than I do will post something which does.