user & group permission

As part of the tightening security plan, I'm somewhat tempted to remove most of our users from the informix group. Since we mostly use r4gl, isql, 4gl debugger, it seems backend programs (fglgo blah) are run ok, even user is not in the informix group. So who is really _need_ or _should_ be in the informix group? Development people sound like the ones, but what if I also remove them from the group? Thanks. Chris