The Franchi is great shotgun, it's pretty much a Benelli M2 with a few minor tweaks. The SX3 is a power house and it will not let you down. I've tried the SX3 with 3/4oz. loads and they cycled perfectly, I cant say the same for the Franchi or even the Benelli SuperSport for that matter.
Both the Franchi and SX3 models I've used are field models so I cant lend much of a hand on the Sporting versions of either. But I know a few people who have about 20K rounds through their SX3 without any stoppage.
Both are great guns and should last a very long time. I would also recommend a quick look at the Fabarm XLR platform of shotguns, all use the same gas system, they just have different cosmetic features. the Velocity is a step up from the Benelli SS and is getting perfect reviews all across the states.
Good luck in your quest.