I have pretty extensive experience with the Scala Q2 Team Set.
My wife and I each have two Bluetooth modules (that way we always have a fully charged spare), and we each have Scala headsets mounted on three different helmets. First let me say I am DELIGHTED with the Scala Q2 system. Second let me say I can't wait to get the new G4 system. If you're a first time buyer, spend the extra bucks and go with G4 from the start. The upgrades from the Q2 are well worth the money.
CAVEAT: I say I am "delighted" AND I confess to "extensive experience." The two factors are definitely related. "Knowing" the system is essential to getting all the benefits it has to offer. The learning curve on the Scala system is pretty steep. That's because it has only four (4) buttons on it for performing about a hundred different functions. I Xeroxed two copies of my instruction manual, and I carry one on each of my bikes. For example, I rode for several days recently with another Cardo Scala owner who will ride ONLY with a half-helmet. At highway speeds the wind noise in his microphone is painful to my one working ear. And the wind noise is sufficient to key his VOX and KEEP IT KEYED all the time. So I hauled out my Xeroxed manual and learned how to KILL the automatic (VOX) microphone keying on his microphone. We can still talk. He has to push a button to key his mike, and when the conversation is over, one of us can push the same button and kill the connection-- AND the noise in my ear. The VOX on MY headset was still active, so all I had to do was talk to key the connection.
You will not believe the quality of the communications from this system--or the other benefits, either. But at this point I have to do my instructional piece.
The positioning of the earphone/speakers in the Cardo system is CRUCIAL. The complaint I hear most often is, "It's not loud enough."
BULLSHIRTS!!! It is PLENTY loud enough for anyone. But you MUST have the earphone/speakers perfectly aligned with your ear canal, AND you must position the earphone/speakers as close to your ear as possible. For the "closeness" adjustment, I cut pieces of soft foam to the right thickness and put them BEHIND my speakers to push them out close to my ears (only one of which actually hears anything). Then, for the "alignment" exercise, after installing your speakers where you "think" they should be, you need to turn on the built in radio or hook up your MP3 player and get a source of constant volume sound. Put on the helmet and move it around on your head-- up/down, right/left, forward/back. You'll discover that the most perfectly placed speakers will produce lousy sound if they are off by as much a one-quarter of an inch. When the speakers are properly positioned in your helmet, you will NEVER use the highest volume setting on the Cardo unit.
Conversation between my wife (on her Harley) and me (on my Gold Wing or my C90T) is easier and more relaxed than a chat in the front seat of our Volvo. My most frequent coplaint to her is, "Stop shouting; I hear you just fine." (Not her fault; she's just shouting over those blatty, loud Harley pipes.)
Cardo builds great gear. We wouldn't ride without it.