When my wife and I ride together (on separate bikes), we use a set of Interphone F5mc Bluetooth radios installed in our Shoei Neotec helmets. Interphone makes speakers and boom mikes specifically designed to fit Neotec helmets. They also make them for Schuberth C3 Pro helmets but I haven't tried those.
In the Neotec, the specifically designed speakers are easy to install and are positioned properly. They are close to the ears and centered correctly. Volume can be painfully loud if you turn them all the way up without wearing ear plugs, or if you do use ear plugs they are still very audible. The boom mic is thin and unobtrusive. You won't even notice it's there.
As an intercom, the radios are full duplex, which I prefer, and voice quality is very good. I haven't tried listening to music with them, but have used them to listen to voice prompts from the Nav system, which are loud and clear.
Range seems to be at least a half mile, and more if you don't mind some static creeping in. We have used them for around 8 hours at a stretch without running out of battery charge. I don't know how much longer they would have kept going beyond that. They recharge very fast.
I like that they are physically smaller than some other similar radios on the market. They have been very reliable for a couple of years now.
