Surprisingly good back - up?
Happy to fly with single "official" source, but have surprisingly good back - up with Garmin 496.
The instrument page gives all you need to continue, as long as you remember that everything is GPS - derived, particularly height.
Important point is before you commence flight you need to have it turned on and programmed with route, and then scroll through each page, accepting info by "enter" on instrument page and terrain page. You don't want to have to start scrolling and accepting after the vacuum falls over and you are in the midst of weather.