My experience has been with the “Allora MXPT-5801-BK Black Nickel Series” that I bought from Guitar Center.
The assembly is very good, and the lacquering is pretty good as well. The valves are smooth enough.
Alignment on the valves is also very good. The included mouthpiece fit the horn and it wasn’t bad.
Mine slots so wide, you can drive a truck through it. Since my Buescher horns are designed that way too, it doesn’t bother me. You might think otherwise.
For a 300 bucks, it’s a very good deal. A friend warned me to not expect a whole lot from low notes since the bell is pretty small. I haven’t messed with it in a while. What I really want to do is try it in my next community band rehearsal.
Roy Campbell uses a pocket trumpet..and I’ve seen pictures of Jeremy Pelt with one. Also Frank London of the Klezmaniacs. Of course, the most famous of all pocket trumpet users was the late great Don Cherry. Pocket trumpets are notoriously hard to play in tune.