I have the Montana 650t and added the Birdseye satellite imagery to it. I'm going to pick up some huntinggps maps as well this year. I can't imagine any other features you would want in a GPS. The location/communication features of the rhino are nice. But the only real complaint I have with the Montana is the size/weight. I see no need to carry a paper map ever again with the modern GPSs. Besides, one of the key features of the GPS is that it tells you where you are on that map. I've stepped foot into areas for the first time and been able to navigate them like I've been hunting there all my life. I wouldn't have that kind of confidence with a paper map.
My view is that a GPS is a tool that can fail, I'll always have a map and compass.