I can't begin to imagine this being a good design especially if you get in a crash. Not to mention it will screw up your helmet aerodynamics, and frankly looks like crap
Chronos is correct in that it will require one set for each bike; However, to each his own! I have the Chatterbox GMRS-X1 and love the fact I'm not "Teathered" to my bike. Having a chord run from you to your bike can in my op be a bit discomforting.... One thing is for sure, you won't be dissappointed if you and some friends get a communicator set-up amongst you! I listen to mp3's, radio, talk on the phone, Radar detector, etc... You can even have a private conversation with your passenger. But, this would envolve and extra set of headphones/mic, plus the dreaded teathered chord. Changing Channels is rarely needed as was pointed out! There have been a few times in congested areas of living where a channel swap was required and I think one other time when my group was riding through rural America! Kept picking up two combines working in a field talking about Green Acres kind of things..... Range is fantastic. Makes for passing cars in really tight/blind situations Great! Especially if everyone in your group has this set-up. You can talk back and fourth and let everyone know when its safe to pass. Most should come with VOX and PTT. If you get a helmet mounted setup try and remember to turn the thing off if Nature calls and your roadside.
Some set-ups to consider
Autocomm (by far one of the best)
J&M (Pricey, but still top notch)
Collet (Heard good things, not so pricey)
Chatterbox (mid level if you get the GMRS)
Audioboss (another mid level set up)
Nady (low end, but I guess it works)
Baehr (Can get real expensive)
Starcom (mid range)
There are more but, this is all I could think of off the top of my head! The most important aspect of any set-up is going to be the Headphones/Mic. I can't stress enough how placement and quality of this single component can make or break your system..