I bought a new Eagle last year, much better than previous unit.
Look for the 12 channel Rockwell receiver. Most good units now have this. Mine will lock on to the satellites inside my house.
Old unit needed a clear view of the sky. With these you do not need an separate antenna. Mine works fine on the seat of the car.
I have a Magellan color track. It is a 12 channel receiver with a color display. It will lock on and track the satellites from my console of dash mount without an external antenna. The 12 channel is the way to go. The other thing to consider is if you want a road map data base of not. My GPS does not allow you to upload a real road map. Many new units have them installed and allow updates to be uploaded. I can always plug into a laptop computer to get the real road map view, but who wants to take up the passangers seat with that. If you only want it for off road and not help getting to the off road site then a map data base can be skipped saving about a $100. Make sure that you check out the number of waypoints and routes that it can store also.