My wife got me an Affinity 3 (12 gauge) for Christmas (with some coaching from me haha). I was between the SX4 and the Affinity 3. Came down to fit, I just far preferred the slender, sleek feel of the affinity 3. Plus I love the feel of the Benelli/Franchi stuff mechanically. But so far it’s run old, cheap, Bass Pro/Herter’s brand 8 shot 2 3/4 shells with no hiccups or hesitation. Most inertia guns I’ve researched recommend 1 1/8 oz shot as a minimum, and won’t guarantee reliable cycling with 1 oz loads. No clue if the gas guns are the same though, so that might be something that’s true across the board.
One consideration if you go with an inertia gun is the increase in perceived recoil. I love my Franchi, but I tried some 3” 1 1/4 oz 4 shot shells through, and oofta, I felt that. I’m not a small guy (6 feet tall, 200 lbs, broad shoulders and chest), and man it woke me up. The Franchi is a great gun for packing and shooting casually, but for heavier hunting loads, if your kid isn’t very big, be warned. It’s not murderous, but definitely kicks more than I was originally prepared for.
That said, I don’t regret the decision at all and would highly recommend the Franchi.