I make no apologies for being a conservative engineer
I was amazed to find that there were companies operating similar aircraft to mine who didn't have ETs or did very limited analysis along the "dump at 1,500" line.
I suppose I'm lucky that we still appear to have a stock of conservative engineers. Flying NW out of Islamabad, we'd get initial and subsequent ETs but also restrictions on AEO achieved altitudes, maybe requiring en-route holding, plus a critical point and precise instructions on how to fly the driftdown or emergency descent. I was gobsmacked to find not everybody had this...
Regarding OEI FMS departures:
Correct. Provided you factor in potential map shift, and many more possibilities.
Those possibilities apply to all RNAV procedures, not just OEI ones - it's perfectly possible to hit a mountain on a normal RNAV SID/STAR/APP but one would hope an ANP alert would have gone off long before the GPWS.
We used to have coded ETs for some airports but they all appear to have gone to make room for the plethora of RNAV arrivals and departures required.