For me it would be worth it. Main because if i had that I would be happy without the rest
Your aircraft earth isn't really an earth its just zero PD compated to the supply the actaul aircraft can be way above zero relative to the "earth" in rotorary and a quite a bit less for fixed wing. You do get protected earth buses for some essential system in bigger things.
As for the life items yours might not be, some are. British designs tend to be lifed items. Even if they would be on inspection under other authorities. Cessna seem to be going the same way though these days.
Outside the aircraft world engineering if you have two system which do a job its always worth having an age /cycle split between the systems because things tend to wear out at the same rates unless you stick in a sacraficial adjustor to make sure one fails before the other.