After 4 months I'm starting to really like the Montana. I have the 600, without the camera.
Tracks work best, though I'm still playing around with routes. Be careful of using waypoints as I've gotten error messages when using GPXs with more than 50. The more I use it, the more features I find.
Plus: Large screen, easy to manipulate with gloves, flexible routing (track back, reverse), great battery life
Negatives: waypoint limitations; when downloading track files, they load onto the device with a generic name ("Track"), so you have to manually find them and rename them; terrible user instructions.
I would also advise the City Navigator add-on pack (on the micro-card) and the Ram handlebar mount.
You also have to become adept at using MapSource software, the best way to interact with the unit for complex trips...the software isn't bad, once you figure it out, but is not intuitively obvious.
One other caveat; After a short time, the unit acted up; when plugged into the bike, it kept reinitializing. When running on battery power, it would send an error message every 30 seconds. When I removed the battery and ran off accessory power, it worked fine. Garmin replaced my unit and it is now working fine...but, be aware, I've heard lots of stories.