Or now that I think of it, here's another possibility:-
Replace the panel-mounted Garmin 396 (which has now been discontinued, and who knows how long the manufacturer will continue supporting it -- Garmin seems to have a pretty poor record in this regard) with an iFly 720, which does the same job but seems to have a lot more features and a larger screen, and use the 396 as the backup.
Anybody got real-world experience using the iFly?