They're both really good. I prefer my 1301 tactical Gen 2.
The minor quibbles with M2 Tactical:
1. FTE when shouldering hard (common to inertia operating system), I can make it fail to eject with 3" shells 1oz slugs by shouldering firmly, let alone light bird shot.
2. Shell latch is super stiff compared to 1301 (makes twins loading a pain in the butt)
3. Charging handle too small (preference)
4. Bolt release button too small (preference)
5(?). Recoil is slightly higher compared to 1301 blink system (might be in my head though, The pad on a Magpul SGA stock is softer than the pad on the Benelli. Not a fair comparison as I've never shot my 1301 with the OEM stock).
Minor quibbles with 1301 Tactical Gen 2:
1. Stock Charging handle feels super flimsy (I haven't broken it... yet)
2. Cross bolt safety is in a non "standard" location (I would've preferred it located at the rear of the trigger guard like a Remington, Benelli, etc.)
3. Shell release/Bolt catch combo button is in a terrible place (located in front of trigger guard at the rear of the lifter)
4. Dirtier than inertia system. Carbon build up around the gas piston area, etc.
5(?). Recoil spring is underneath the foreend (I suppose this makes it more susceptible to the ingress of debris that can cause malfunctions, but I'm not dragging my 1301s through mud, nor do I live near a desert.)
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The user induced malfunctions that can occur when shouldering too firmly (of which I have a natural tendency of doing) on the inertia system is what makes me prefer my 1301. No FTF or FTE with my 1301s yet (both Tactical Gen 2 and Comp). However, I honestly don't think you can go wrong with either.