It's a matter of quality over quantity [of players], and personally I always opt for the former. Go with whatever feels right, but keep in mind you're seriously handicapping yourself by making it retail compatable in this day and age, which is what I assume LGMobius was getting at.
I'm assuming that's what LGM was getting at too, but there are some (not many) reasons to keep using retail. Some people don't have computers (or video cards) that can run the SCP; some have the unfortunate luck to keep running into bugs; some, like Cobra, can't install the SCP correctly; and some, like Selectah, refuse to use the SCP on philosophical grounds.
There's also the legacy support option. We're keeping ST:R compatible with retail because the Port'ed Main FreeSpace Campaign and Silent Threat are compatible with retail. Not providing FS2-compatible versions for campaigns that worked on FS1 would be a dumb decision IMHO.
That doesn't preclude us from using SCP enhancements, of course. Version 3.0 of the Port has tons of improvements that work in FSO but are simply deactivated in retail.
