Here is a recent interview of Roger Waters where he tells the funny story about how he made a deal with David Gilmour to appear on one of The Wall shows.
I'm mostly the original Pink Floyd fan and I really believe that together they were way better than separated. Fortunatelly both Gilmour and Waters still do their shows which are absolutely great, so we can enjoy the music of Pink Floyd even if the band no longer exists… And yes, The Wall is the great show. Not only production-wise, but music-wise equally. And I have to say that credit for that goes to Mr. Dave Kilminster.