I have never had a 276 but I have a similar 496 in the dash of my airplane to back up my Garmin aviation stack. In addition to the thing you pointed out I miss a couple of other features with the Montana. 1) Routes I down load from BC can't be reversed. If I lay out the route on the Montana I can reverse it. 2) If I have a route lets say with 10 waypoints and part way through I want to skip a waypoint and go to one farther down in the list I can't. On the 496 I can go to the route list pick any waypoint and go to it.