I have used a Garmin 550 unit now for about four years and it is awesome. Super reliable, far better than the 660 unit, it locks onto the holder so you can't get it nicked when left overnight when you are travelling, and it works really well with the mapsource software.
They are slightly bulkier than the 600's, but have been super reliable. With one techmount bracket, and several sets of power leads wired into each bike's battery, it is a two minute job to pop the unit on whichever bike. It is out of the way of the bike's dash, does bluetooth reception to your in ear speakers (but I don't bother anymore I just look at the screen) and is one of the most useful things I ever bought.
People used to laugh about four years back when I put one on the 848. Now they are everywhere, and for good reason.
Sod map reading. Do that at home, then pick the route, light up all the twisty bits, hit download and go. You can ride for hours on end without even having to think about a map......
Every time I look down and see the bit marked out with a superb pink wiggly line, and the mark "25mls til next turn" I just think "game on!" and wind it up without having to think about anything else.....
