Poly chokes are an ugly stepchild to many of us and that's a shame. They do what they say they do, adjust the pattern as needed.
But, they also add weight as the muzzle. Sometimes more weight than we like. If the term "Muzzle-Heavy" was in the encyclopedia, the picture next to it would be an A-5 with a Polychoke.
Some of us find the "Onion" at the muzzle distracting.
And, some were installed off straight. These won't pattern in the right Zipcode.
However, many older shotguns come with them, the extra weight for some is a plus factor in keeping the swing going, and the fast, tool free adjustment is good in field and blind.
Slugs can be shot through them IF the thing's set for an open pattern. Legend has it that the "Petals" break off if a solid ball is fired through a Full Setting. Open will almost certainly give better accuracy anyway.
And the marking are oft just approximate. Patterning is needed to find out where the real IC, Mod, etc, lurk.
HTH.....