I've looked at some of these, such as the Magellan Crossover, but I see a few problems from a survival and/or field use standpoint:

1 - they typically use rechargable batteries. If you're only using it in a car that is no big deal, but if you want to bring it into the field then that is a problem. I personally like units that allow use of common batteries (same thing for digital cameras by the way).

2 - some of them don't seem to allow entry of waypoints as coordinates. I could be wrong on that though. I'm not sure if they let you save a waypoint for your "current" location.

3 - some of them may not allow selection of different datums to match the paper maps you're using (or that you're getting coordinates from).

4 - so far I haven't seen any that allow use of UTM coordinates, which are VERY handy for field work with USGS Topo maps.

These were the main reasons I went with the Garmin GPSMAP 60CSx rather than an automotive-type unit.