The new G4 model is very similar to last year's Q2 model, however, Cardo claims the effective range has been increased from 500 metres with the old Q2 units, to 1.6 Kms with the new G4 system. The new G4 also has a built-in FM tuner and supposedly better quality speakers. The documentation said that the new units are backward-compatible with the old ones, and we managed to pair our two units together in about minute -- after consulting the owner's manual, it was quite easy.
Being able to talk to each other while riding was really great -- having never experienced it before, it's hard to describe -- it's just one of those things a person cannot understand until they can do it themselves. From this point onward, going on a motorcycle trip without it couldn't be the same. How did I ever manage without it? Full-duplex, crytsal-clear, voice activated communication -- just like talking on the telephone. Who'da thunk it? It's amazing.
And when I wasn't talking with Sean, I was able to connect to my iPhone via Bluetooth, and use voice commands to listen to music, or to initiate/receive telephone calls using voice commands (ex: just speak the command "play -> AC-DC -> Highway to Hell," or "Dial -> Smith, John -> work number"). The shit just works, and it works over Bluetooth -- no wires! For shits and giggles I called Brad -- a buddy from work -- as I cruised along the highway at 130 Km/hr and he remarked that sound quality was excellent.
I even wore my ear plugs during our entire trip (as I always do) and I was able to hear no problem. The G4 units automatically adjust the volume for you - it's that easy. If you don't have a Bluetooth communication system, then you need to get one. It's a no-brainer.
In this photo you can see that I have the antenna flipped up:
not required unless you really want to get the most range out
of the system.