Ok, I didn't realise that feedback would be an issue with headset mics.

Well I'll have to audition the Mic with the Bose (fortunately the store I'm buying from has one permanently set up (they are Bose distributors) so at least I can see if there will be an obvious problem.

Incidentally I've been using Shure headsets for some time now (years) so I'm completely sold on head-worn mikes per se.

Thanks for the advice fellas!