I just finished yet another round of real-life testing with Bluetooth comm systems. I bought (with my own hard-earned money) a Sena SMH-10 BT system and used it with a Zumo 660 GPS in both solo and 2-up rides. After a few weeks here's some quick thoughts for you to consider...
* The new BT systems (like the Sena) work pretty much as advertised. Be sure to download their user manual before you purchase, then sit down for a long read. If you don't clearly understand something, send email to their support. How well they explain and answer your question(s) will determine how much you like the unit after you purchase it. I can say that the Sena unit works almost EXACTLY as specified in their manual.
* IMHO, Bluetooth is still best-suited for solo riders. The "switching" that's required to do rider-passenger intercom or bike2bike is at best, awkward. Once you've used a wired system like the Starcom1, both rider and passenger will miss the open, full-duplex communications of wired systems.
* Weigh how much use you'll get from the Bike2Bike, against the money you're spending on the actual units. Midland makes some decent water-resistant units that sell for $80/pair. If you know you'll be using GMRS/FRS for Bike2Bike all day long, every single day, then by all means spend the big bucks for 12v-powered high-end radio.
* Cables are a total PITA, so is having your helmet smacked because you can't hear her yelling, "Stop that! I have to pee!!!". Life's full of compromises.