Is it just for the trails, or do you want to use it for street use as well?
Silverfox got a Garmin Oregon a while back.  It has the ability to upload topographs on it and overlay trail maps I believe.  I know he liked it when he first got it, maybe check with him now that he's had it for a while.
The Oregon series only has a 3" screen though, so its a bit small if you want to use it for street driving.