I can give you some positive feedback.
I don't know why this choke isn't getting the love that some other chokes are, but I bought one a few months ago and I absolutely love it. I did polish my barrel and shot about 75 rounds of AA target loads thru it before I got serious about shooting my stash of Fed 7's.
Remmy 870 youth. 21" bbl. on a clean barrel I get a nice EVENLY dispersed pattern in the mid 150's. 2nd and 3rd shots may go into the 160's, then it starts to diminish. This was with temps in the low 60's and humidity at about 65-70%. I don't consider the pattern to be overly tight as much as I would just say it's very, very even.
I decided to go sumtoy or trulock because they will work with you to get what you want out of your set-up. Just happens that I got the Trulock first and hit it good right from the start. Other chokes didn't seem to throw consistent patterns from shot-to-shot when taking a look at some of the pattern pics on here. Other folks guns and mileage may vary. I would say everyone should give this choke a try, they really have the FC wad figured out for the 12 ga. and it appears that the 20 choke is a winner too. Don't like it, send it back.