I like it on the bars, Normally I have the trip screen on which has all the normal goodies: MPH, odometer, etc, etc.
Yes the buttons aren't the greatest, but it's water proof, and with the summit the only button you need is the little joystick thingy which is a lot easier to use than I thought it would be. On the bars it's quick and easy to flip to map to make sure you're heading back to the car when you want to. It's been absolutely necessarry the last couple of times we've gone out as we've gone to places we've never been. That is no one in the group had a clue where we were going or where we'd been. Whoot
As for the handlebar mount, just plop in etrex handlebar mount in a google.com search. You'll find lots of places that have them now. 6 mos ago you couldn't find them anywhere. I just looked and you can get them from $14 to $20. Shop around.
-MD