If you only want voice input and no mp3/cellphone etc I'd recommend the same system as the military pilots used, throat mics with a single headphone in the helmet and some uhf radios. Like you mentioned there's no road noise and tho the voice comes through a bit tinny it's clearer than the full voice plus engine noise, wind etc. Get a radio that will take a push-to-talk putton and get weather-proof buttons on the handlebars - the VOX systems aren't that reliable and if you start mumbling or singing in the helmet it can be embarrassing - specially if you're mumbling about that cute girl that's on the sidewalk and your wife's listening.
Matt
