One feature which is quite useful in Garmin's GNSxxx are the VNAV indications. Either having an alert ("start descending 500fpm to reach 3000feet before next waypoint", with "500ft" a customisable setting and the waypoint and altitude coming from the plan) or an onscreen field giving the fpm required to get to the planned altitude at the next waypoint. The latter may add confusion to the MD screen but would be fine on the iPad version