I have a homebrew Mossberg 930 that I set up for 3 gun, prior to the release of the JM Pro models(might be a ancient thread on Pirate or Brian Enos). I can straight up John Wick with that gun. I run reduced recoil buck and slugs, that I carefully tested for reliability and accuracy(Shot a shit ton of options, huge differences in accuracy). Mine is a little shorter at 22" than the JM Pro. I had the barrel chopped, forcing cone lengthened for improved patterns and reduced recoil, and then threaded for chokes tubes. Opened up the loading port, fiber optic rifle sights, extended mag, oversized safety, etc. Sure I'm missing some stuff. I ran it trouble free in matches for 2 seasons, before work started interfering with my play time. It would be one deadly beast if needs be.
Personally, I've been on a shorty kick. Subguns/"pistols" and bullpups. My current bed gun is a tricked out Keltec KS7. It's petite and I have it stuffed with a shit ton of mini buck and slugs. Choke tube adapter, tuned trigger, RDS, light, etc...
Either way, I'd hate to be on the receiving end.
FWIW, no matter the choice I'd recommend finding some reduced recoil or mini's that it likes. Nobodies gonna miss that 200fps, and it makes it way easier to shoot well. I hate, hate, hate, patterning hot 3" loads, especially out of that little KS7! (gonna try and take a yote and turkey for kicks with the KS7. No pun intended!)