I stocked up on the IMI 77gr SMK's back when they were $0.50 a round at Midway (Salad days), along with some Frontier 75gr loads. That was for my 12.5", 16" and 20".
Going in, I knew it was a good, but not great, defensive load. It is basically a better M193 in how it operates.
The shorter the barrel, the shorter the total fragmentation range, and most likely, the longer the neck.
It is not barrier blind (which was a plus for me).
77grs TMK's are better, but probably even less barrier blind, and are starting to become harder and harder to find (again).
In the end, something that expands instead of fragments will always have a place as a top defensive load, given that expansion is usually more consistent, are barrier blind, and allows for a longer expansion ranger than rounds that fragment, although I prefer fragmentation.