We have a CAA-approved policy to use MDA as a DA but only if using CDFA. We went through a long period of confusion where sometimes we added 50’, sometimes we didn’t but after some solid technical work the Authority supported our safety case.
From a practical POV, there is a considerable difference between following a NDB needle on a dive’n’drive and a stable RNAV approach on a RNP-capable aircraft with GNSS, EGPWS, etc. All our planes are equipped for the latter.
Looking at recent incidents (Air Canada springs to mind) it’s what you do *after* MDA/DA that seems to be more of an issue. A prompt go-around does the trick whether it’s MDA or MDA+50’...