I haven't yet... although I asked lots of questions about it with the J&M folks at the NYC motorcycle show a few weeks ago. I've already got 2 of their Elite series headsets, and the GL1800 GPS/cell phone/radar detector integration unit on my bike.
The neat part about it for someone like me who rides solo 90% of the time is that I don't have to equip both front & rear seats with it if I don't want to. Each headset position uses a separate transmitter, so I could save money by just purchasing an un-corded setup for me, and retain the status quo on the rear seat for those few times I ride 2-up.
However, I admit that I too am waiting to see someone's else's results with it before I pull the trigger... espcially in light of the fact that it's not returnable/refundable.
If I understand their policy on Bluetooth items correctly... once you buy that sucker, it's yours, regardless of how well it works on your bike, or how well you like it (unless there's a defect in the product, that is).
Of course, if John is watching this thread and he'd like to comp me a setup for review... I'd be glad to post my results for everyone!
