After some research and much debate I chose a Garmin Zumo 450.
Several Philadelphia Riders own the Zumo and I understand routes can be shared. Knowledge can also be shared. The Zumo and TomTom Rider are strong motorcycle specific GPS offerings.
The only difference between the 450 as far as I can tell are a) car mount and power ($65 and $25 respectively online) b) Bluetooth c) XM
the 450 can receive traffic broadcasts. I mention this as it was a feature I was looking for.
The Zumo comes with standard RAM mounts. It was *very* easy to install on my MZ Skorpion Tour. My bars are stock though mounted a little lower on Vortex clip-ons. I added crimp on connectors and attached the power leads directly to the battery.
I did order the car kit. My total cost was about $602. The Zumo 550 is $660 on Amazon right now.
TODO: add part numbers for car kit and power adaptor.