I've largely moved over to TSS. I found a sweet spot with a 12-3-1.75-9 and an Indian Creek Choke with an exit diameter of .665".
As noted, this Rob Roberts choke worked very well with H-13 #6. I have a big stash of the "Old White", which is a 12-3-1.75 load containing true 13g/cc shot. With that load in typical turkey hunting conditions, I'll average in the mid-140s in the 10". Current production H-13 #6 in the 12-3-2 load would yield results in the 150s. Of course, in warm weather and high humidity, the 10" numbers will jump considerably. There, it's not uncommon to see patterns in the 170s with the 2oz load.
That said, Rob's strategy isn't to build chokes with "eye-popping" numbers in the 10" ring. Rather, he works toward producing an even pattern that has an effective width of 12-15" or so. So, if simply maximizing numbers in the 10" is one's strategy, this will not be the best option.
I really liked this choke and found it's sweet spot was with H-13 #6s. It also did pretty well with H-13 #7s too. As I recall, it'd put in the 180s in the 10" in cool weather typical that you'd expect during turkey season. However, patterns looked great out to 16-17". I'm sure one could drop down to his .655" with the #7s and get higher numbers in the 10", but effective width would be sacrificed.
