Great write up indeed. You, along with ChinaV's ever wise words, have made me interested again. Looks cheap and simple enough. Couple of questions about the setup:

Could you route the 3 cables along the helmet so that they all come down from one point, using duct tape or other precision engineering?

Do you have to keep the button pressed in as you're talking? It just looks like it might be a bit awkward to talk for very long with the button where it is.

Is there any possibility to listen to music through this system, other than the radio? I mean like hooking up an mp3 player. As ChinaV implied, a happy wife...

Finally, nice bike! I think i've seen one just like it on this forum before! +10 on the visibility tape, you've such a large area at the back of that bike, good way to use it. I once went down the same road with my scooter and got a bit carried away...