Most people that buy a M3 know what it is and wants that selective action capability. Personally, I am not going to be shooting CS shells or beanbag rounds, but I do sometime shoot lightweight loads because they are cheap. I also have an affinity for semi-auto/pump guns. I also am a big fan of Franchi SPAS-12 (as long as it has had the safety switch upgrade) and SPAS-15.
I always loved Benelli because they were NOT gas-operated. Simplicity, lighter, narrower forearm, and easier cleaning area all great features of inertia system. I bought my first Benelli brand new in ~1994. It was a HK import SBE. Within a very short period after I bought it, all other shotguns except for a .410 were sold. It didn't take long to figure out the quirk that it required 1 1/8oz dram shells but it didn't matter if they were name brand or high brass. It shot Wally World cheapo stuff as long as it was 1 1/8oz. Since then, I have bought a pair of M3T folders, M1T, Montefeltro 20 gauge, and have bought and sold SBE II and III. I finally decided I'd get a couple M4's too since I had most everything else I wanted from the brand. I got a standard pistol grip model that had been converted to full length mag, collapsible stock, etc. I also bought a NIB 11711. To me, Benelli IS inertia driven. The M4 is a fine gun for sure They may be the better choice for those going all out with the tacti-cool look with tons of gadgets hanging all over (which I am not really in to anyway).