Never heard the M97's aren't made for modern 2&3/4" shells. Mine was made in the 1950's (not long before they stopped making them). Certainly the later ones handle standard/modern 2&3/4" shells just fine.
The M97's and M12's (the take down models anyway) break exactly in half and store/carry in a shorter space/case. Most other pumps allow you to remove the barrel but the magazine tube stays on the receiver.
A long time ago, I would carry my M97 on some stakeouts. We didn't want the public to know we were in the building/watching so I'd break my M97 down, tie a nylon string/cord (one end in the trigger guard and the other through the gap between the magazine tube and the barrel) and hang it over my shoulder under a raincoat/long coat and carry it into the building with me. When I got where I was going (base of operations for the night) I'd pull the coat off, put the M97 together and load it up with 00 buckshot. In a blacked out building, in the middle of the night, when you're searching floor to floor for people who shouldn't be there (but could be there trying to steal electronic equipment/computers) that 12 ga. is very comforting. More than one time my partner (when I was working with one) would tell me how much better it made him feel to know I had that short barreled 12 ga. in my hands.
I've seen fairly nice M12's at gun shows for as little as $300. Damned near bought that one. I just don't need anymore shotguns I won't use much. I have a nice Ithaca 5 shot and 8 shot 12 ga. that I don't shoot now.
While it's not a pump shotgun, I got an old Browning Auto 5 a few years back and I really like that old shotgun (another fine John Browning design). I wish I'd run across one like that 40 years ago when I was bird hunting hard with the dogs. I think I would have enjoyed it (M37 was my shot gun back then). Not to replace the M37, but to alternate with it. There are popular (for modding) copies of the Auto 5, too. Remington made the M11 and somebody else (Savage??) made one, too. Not sure about parts availability/commonality between the Auto 5 and it's copies, but the Auto 5 parts are available (if you ever need them. All I did to mine (1934 production with a ton of use on it when I got it) was replace the springs and a couple butchered up looking screws (also replaced the old worn almost smooth stock/forend with synthetic pieces and removed the rust coating with oil and 0000 steel wool rubbing.) Oh, put an extended magazine tube on it, too. Holds 9 rounds of 00 buckshot now.