I own two UC-9's (I liked the first gun so much I got a second one) and a full size Thunder 9. The first UC-9 is almost 4 years old, has several thousand rounds through it and has
never had a single problem of any kind. I used it the last time I qualified for my CC license, scored 248 out of 250 and plan to use it again when I renew my license next year. My second UC-9 is about a year old with just over 200 rds through it. So far, it's performed just like it's older brother and I expect it will continue to do so. As for the full size 9, I've owned it for almost three years, I like it and it's as reliable as the compacts. However, after owning a full size and compact Bersa 9mm, I'd recommend the UC. It's smaller, easier to carry and conceal and still holds 13+1 rds of ammo. For me, it simply a better overall package.
FYI, a company called Eagle Imports is the importer of Bersa firearms into the US as well as being the owner of the Firestorm brand name. Bersa S.A. is a stand alone company that builds it's own guns in Argentina. OTOH, Firestorm doesn't actually make
any of the guns sold under it's brand name. It's really a gun "company" in name only that imports several different makes, models and caliber of pistol (and a revolver) from a number of gun makers. Bersa is just one of those suppliers and EI sells them under it's Firestorm brand name with the other makes/models. The only noticable difference between any Firestorm pistol made by Bersa and an actual Bersa of the same caliber/model is the shape of the trigger guard. A Bersa gun has a tactical, curved trigger guard while all Firestorm trigger guards are the more traditional rounded design. FYI, all parts between Bersa/Firestorm guns of the same design and caliber are interchangable.
One more thing... don't confuse the bigger caliber Bersa guns (9mm and larger) with their 380 pistols. They are totally different in design. The 380 and smaller caliber Bersa's are fixed barrel, blowback pistols that are simply updated Walther PPK's. OTOH, the bigger caliber guns are based on Walther's P88 (think SIG if you aren't familiar with the P88).
As I told someone not long ago, I have a dozen different 9mm pistols from full size Rugers to Kel Tec's PF-9. If I could only own one 9mm for all situations, it would be my UC-9.