Well I reckon this one is another example of Fords and Chevys. I have been using both factory and personally loaded Speer shotshells in various calibers for 30 some odd years now, with total success. Normally I have used it to shoot poisonous snakes that want to play, but I have also used the .38/.357 load to kill a very irritated possum. He had been caught in a trap set in a homeowner's attic. The slant of the roof where the possum was made hitting it effectively with a nightstick impossible, and it was in the process of biting through its leg to get loose.
I was checking the Speer reloading manual for some info requested in a pm I had received, and noted the following guideline on shot spread. With loads filled with either 7.5, 8 or 9 shot (which is what Speer suggests for loading their capsules) they state to expect a spread of about 1" for every foot of distance. So at 10' you should expect about a 10" shot spread.
Most factory rounds are loaded with no. 9 shot, and I have used mostly 7.5 shot in mine with some no 9 shot. But I have used both with total success, and have not had to be standing on the snake I was killing. I normally shoot at least twice, and shots fired from about 3 to 5 yards have probably been my norm.
Like I noted, some folks like these, some do not. Count me in the group that appreciates these rounds.