I have the full face helmet outfitted with a Scala Rider G4. I use it with my touring bike, for communication between riders and also to talk to my wife. The ScalaRider G4 is Bluetooth so I can listen to music off my phone, as well as make and receive calls on top of all the communication between riders. I use earplugs all the time and I actually hear better than without them. I can clearly hear horns and emergency sirens, vs not having earplugs and the wind noise overpowering every other sound.
At first I thought that music on the bike didn't make sense, I wanted to hear the engine. But it is actually pretty nice. I don't have it ON all the time, but when I do it does make my riding smoother.
I recently did a cross country trip on the bike, and having the music was great!
I use the same helmet for the TW200 and I do listen to music when I am on the slab getting to some off road. Once off-road I normally turn the music off. With this setup you get thin speakers that go in the helmet, so I am not putting anything in ear besides the earplugs. I am also not running any cables from the helmet to an iPod and I can change songs and volume with gloves on.