I've been using the chokes on ALL my hunting guns. Hell, my clays guns too! I first got them for my Citori Hunting which chambers 3 1/2's. It looked a little strange having two Patternmasters in the gun, but that one choke did it all. Patters were very uniform as advertised. Then I upped to an Xtrema with a Patternmaster. Finally I ended up getting two Patternmasters on my 20 gage Franchi o/u. Recently I got my wife a Browning Gold Ladies Sporting Clays and traded in my Citori Hunting (no need for it with the Xtrema). I kept both Patternmasters and she now uses one along with her Midas chokes for clays, or if she wants, she can use both on her Citori Sporting Clays.
In short, here's my take, having used them for hunting and target shooting for about 3 years now in three different guns...
They appear to work as advertised. The pattern appears more uniform. When hunting (or clays) I either obliterate the target or I miss it. If it's clay, it's either dust or it's "broken into one piece", very little inbetween. This led me to believe it was shooting like a full choke, but in actuallity it shoots more like an IC, but like someone said, no shot string, everything is right there in a disc rather than a cloud. This is great on zero deflection shots, bang, dead meat. The downside though is on pass shots, you gotta be right on the money. If you are, dead meat. If you aren't, no stray pellets to cripple the bird. At least that's what I've been told and what seems to be true from experience.
With shooting lead or with a light shot cup/wad I'm not sure if they still work the same. They SEEM to, but I have never really patterned them with lead on the range. However, just using the Patternmaster with clay loads it seems to have the same effect, and I've had some spectacular smoking birds out to about 30-35 yards, about the same as a full choke I'd guess. If I do an entire clays course with the Patternmaster ONLY, I'm about 5 birds behind than if I changed out with an IC or SK on pass shots. I do believe it's the short shot string that costs me those extra five, (and my cr#ppy deflection shooting). If I were ever to shoot trap again, I'd be using a Patternmaster probably, assuming it does a pattern as dense as a full, but with the diameter of an IC.
My favorite though is the 20 gage Franchi. My wife or I use this light little 5 pounder when we're breaking corn for pheasants here in Wisconsin. The 20 is nice and chambers 3 inch mags, but of course, it's "only a 20 gage". Well, I can verify that if you are "on" it hits as hard as any 12 gage. I whacked a bird about 40 yards out once and it dropped solid. It was the world's luckiest pass shot too, but that cock was pelletized pretty well. So I do believe in the things. Then again, I hunt with Airedale Terriers too. :shock:
So that's my take. If nothing else... they look "cool".