I purchased one last year for my benelli m2 after trying a jellyhead,puregold. It out performed the others by a large margin. Sold the m2 and got a vinci i kept the SSX to run in the vinci. People said it was to much constriction so I purchased a .650 Jebs in nashville at the convention. The Jebs lack bout 70plus pellets in a 10" as the SSX so I called him and he sent me a .655 and .660. The .655 shot worse than the .650 the .660 shot better the .655 but not as good as the .650.
I've been shooting 3" HS blends with the occasual lead load. The .660 jebs shot a descent pattern with some of the various lead loads I tried so I kept it and sent the other 2 back to Jebs.
I purchased a rhino .660 used it still was not in the same ballpark as SSX as far as pattern density or numbers with the HS blends.
Buddy of mine purchased a tactical benelli M2 and the ssx performed best in his also while shooting HS blends and nitro 4x5x7.
Never run the SSX in anything but a Benelli but they sure like it. Some of the chokes I've shot have cost three and four times what SSX cost with nowhere near the performance in the shotguns or loads I've run.