Given that it's *GhostScript* that isn't "100% PostScript compatible," I'd have to say "no." It's just like some of the original IBM PC clones back in the early '80s -- it wasn't IBM's fault that some of them were only "mostly" compatible and wouldn't run every single application than a true-Blue PC would.
Not that I'm knocking GhostScript though -- it's a great program given that it's free.
These days it doesn't really make a lot of sense for most people. Heck, Adobe figured that out as well when they introduced the PDF standard in 1993. I'd suggest that the people sending you PostScript files in the first place are being rather anachronistic, but of course I understand that often standards and procedures "make sense at the time" (...that they're adopted...), and then companies end up keeping them around due to the NRE cost of changing to something better or just due to plain old apathy (it works for them internally, who cares what the rest of the world is doing?). See also: ORCAD.
---Joel