I bought a Garmin 276c last spring for use with Bizer's Garmin map and was very pleased with the combination. I chose the 276C because I wanted a unit that could also be used it in the car, plus photos on Bizer's website showed their map working with that model.
The Garmin map is not as complete as the C-Map version, but it's still very good. You can get more info and see pictures of that unit in use on their website:
http://www.bizer.com/garmin
And a couple of related threads:
http://www.winnipesaukee.com/forums/...NHskier+garmin
http://www.winnipesaukee.com/forums/...NHskier+garmin