pulluphard
The EGPWS database and GPS both work on WGS-84, so as long as the GPS navigation is enabled in your FMSs, the EGPWS won't be affected by operating in PE-90. However, disable the GPS, so the FMS is working on DME/DME positioning, all bets are off.
Us clever running dogs of capitalism, mapped the world's surface without regard to local authority, but couldn't do the same for things like navaids.
GF