Yeah I think the big difference between the SAW and 240 comes down to the fact that I still had to make entry and clear buildings with the SAW, while the 240 is more of a legitimate machine gun role for the squad. The SAW just gets you some extra rounds downrange when gaining fire superiority.
Yeah nobody seemed to like the M320, but my only experience firing it was on a range with smoke and TP. There were a few M203s in my company but several guys just got the M320 instead. The ones with the 203s got some extra sight attachment but I can't remember it's name.