Hmmm...
Can't quite say I agree with you. Floyd had more than their fair share of prog brilliance throughout their career, and almost all of their albums are at least kind of proggy. For me, their proggiest (and best) are Saucerful, Umma, AHM, Meddle, DSOM, WYWH and Animals. I agree with many of the above posters that DSOM is prog, but I also agree with you that it is their most overrated album, and that the similar sounding WYWH is FAR SUPERIOR. Piper, More, OBC, Final Cut and DivBell are all somewhat prog, and I actually like many of these better than DSOM. Thier poppiest albums are The Wall (one of my favorites nonetheless, and it does have some prog aspects) and AMLoR (my least favorite Floyd album).
Just my view.