I´ve spent about 6 months researching the various options and trying most of them.
If music is important to you then steer clear of Cardo & Midland (i haven´t tested the G9, but if the Q2 pro is anything to go by, then i won´t either)
The main problem with these systems is stereo/mono uncompatibility. The A2DP streaming works O.K (Stereo) until the nav gives a direction instruction (Mono) and the whole plot freezes. This then requires a restart of the bluetooth module every time.
I also have reports of this happening with the intercom on both Midland and Cardo systems.
The american service hotline from Cardo were very helpfull, but advised me to live with it or try the G9. On being asked if the G9 could have the same problems, the line went very quite for a moment. something to do with the priority settings for tel and nav being on the same level?
This paired with coded beep tones instead of clear spoken instruction when pairing, turning on/off and setting up, and intermittant pairing/de-pairing faults (i had to factory reset my Tom Tom a dozen times untill it recognised the Scardo again) drove me to mental collapse!!
I have finally settled for the Sena SMH 10. This is the only system i have found to deliver everything that it says on the box (plus more), along with good stereo sound (the helmet speakers are twice the size of Cardo and Midland) along with very easy use (one dial to to control volume, speach instructions, A2DP (forwards/rewind/skip/pause & play), intercom (if VOX deactivated), telephone (recieve/reject/last number redial), and easy pairing of devices.
Long term test gives 18 hours of non stop A2DP music from my mobile phone with a charge time from flat to full of 3 hours.
Intercom talk time of 12 hours can also be expected in warmer climates.
Bike to passenger communication is very clear well above legal speeds.
Bike to bike with up to 4 participants and a communication distance of 500M on clear roads
Pairs with all mobiles and navs i have tried (i use mine with a Samsung paired for phone audio to my Urban rider (phonebook, incoming calls, recieve/decline etc over the Tom Tom display) and phone A2DP directly to the Sena.
Clearly spoken instructions and settings (even battery status)
Fully VOX compliant for rider to pillion and rider to rider intercom and phone
Updateable (over a windows or MAC based programm that also allows option settings while connected to the computer) with the promise of staying that way (Last update was March 2013 with multi language menu prompts and increased volume (as if it needed that
Options for cable microphones and earbud speakers are available (they even have a headphone version for the old "Puddin Basin" type helmets)
External 3.5mm plug for connecting an audio device /(or whatever else you want) directly (this one gives the music quality 1 to 1 to the speakers, unlike the Cardo system)
On turning the system on or coming back into range (i.e after paying for your fuel) it takes about 5 secs to re-pair with my nav and phone, and even tells me (in clear speech) that its done it!
Individual volume settings for all channels and devices that are attached. these stay set on turning on/off or going out and coming back into range.
Oh, and the sytem is really LOUD on max volume, without distortion.
I´m writing this mainly because i am very pleased to of finally found a system that does what i want it to, no matter what order i pair things, and even talks to me to tell me i´ve accomplished the setting
I just thought i´d share it with those considering buying bluetooth intercom systems in the future.
I have nothing to do with Sena except as a very impressed and happy customer
I paid €290.00 (from Germany) for the double set containg 2 x combined helmet speaker /microphone clamping sets, 2 x mini usb cables for charging/computer connection, 2 x 12 volt vehicle chargers, extension pads (in case the speakers are to far away from your ears when mounted in the helmet), 2 x helmet sticking pads (in case the clamps aren´t compatible with your helmet) 2 x bluetooth modules, lifelong update, instructions etc
Did i mention that the system is LOUD?