The G4 is awesome, my brother just got a set a couple months ago for him and his wife. I'd like to get one so I can join in when I go on rides with them but DAMN they are EXPENSIVE.
My husband and I have the Scala Rider 4 and used it for the first time last week. It worked pretty good between riders and for the radio. Shop around though I noticed the prices varry at some stores online.
I like my Chatterbox if I'm riding in a group. Especially if it's a large group, big enough to need a designated lead and sweep rider. They're invaluable in that situation. You've got to be able to talk to the leader if you're sweeping and trying to keep a group together.
If I'm riding alone, it's worthless. I hate listening to music and the last thing I want to do on my bike is talk on the phone. So it stays home if I'm on a solo ride or out with just a couple of friends.