I know a few guys in my area who SWEAR by them. On the other hand - I have shot one, personally. I did not really think it was anything special. My BRILEY does just as good a job. You wanted other opinions. Agree or not, this is mine..........
My experience with the Mueller chokes is that they are lighter, and because of the ceramic coating they don't get as dirty on the inside. They do not seem to loosen like the others do. They pattern well, but no better that the Briley choke.
Would I re-purchase them if I lost them? Yes.
I use Muller chokes. I wonder how many of the respondents above have ever tried them. As for whether they are any better or worse; who knows. They cost ten bucks more than a comparable Briley choke. This is a mental game, and if for that ten dollars you think you have a better choke, the psycological advantage you get is probably worth the ten bucks. I personally do like mine.
I have tried them. No better than any other choke. There was one thing I did not like about them is they are longer than other extended chokes therefor you have to remove them to get your 34" barrel to fit in the case. Quite a pain if you ask me. There are better choices.
I had a whole set of Optima’s and found them to stay cleaner than most chokes. I sold the whole set and went back to the factory extended chokes that came with the gun. Scores in trap never changed with any chokes that I have tried. I will say the Muller U2 is a great sporting choke; the only one that I could say really improved my score in sporting. My U4 cracked after 10-shots during a trap round, Muller replaced it immediately and I sold the whole set soon after.
I have a U1 and a U2. They are leaps and bounds over the brileys that I have. Cleaning is a cinch and they do not shoot loose. Also,I put them on paper and they pattern even and consistent. Best chokes for sporting-trap and skeet. Highly recommended.