I recently purchased a used Firestorm for $140. At least, it was in the used display at a local gun shop. It was in pristine condition, and whoever owned it before me took very good care of it or didn't shoot it very much at all, or both.
I have shot about 300 rounds through it with no issues at all. I've ran Gold Dots, Golden Sabers, Sellier&Bellot, and some Speers through it with no problem at all. My hands are just a little on the large size, but the handle is comfortable too me. The rubber grips are just soft enough to provide a really good grip. The sights are easy to pick out, and the trigger is superb in single action. Really, really good trigger. I don't think it has a trigger job on it, but it feels like it could have. The double action trigger is also very smooth, but has a long range of motion, so much so that my wife though it was malfuntioning the first time she shot it because it hadn't gone off yet.
It has functioned flawlessly in my hands, and when two of my friends shot it. It has jammed twice when my wife was shooting it, but she was limp wristing it badly. She's still very new to shooting, but is already a force to be reckoned with when she uses her 9mm
Anyway, back to the Firestorm.
The only difference I see between the Bersa Thunder and the Firestorm are the sights. The Firestorm has the "box with no top" dovetails in the back, were as the Thunder has the 3 dots. The Firestorm is billed as an improved version, although other than the sights, they seem identical, right down to the paperwork that comes in the box. I handled the Bersa and Firestorm side by side, and couldn't have told them apart without looking at the name on the handles.
Its also very flat, and just a touch longer than a PPK. Very concealable, and as small as I can can go and still feel comfortable with the grip.
I'm not just a client, I'm the president! No, not really, but I know this sounded like a hard pitch for the Firestorm, but between it and the Bersa, unless you have a strong preference on the sights, I'd go with whichever one was cheaper in your area.
Wild Bill's makes a concealment holster for them, by the way. I'm going to order one soon, and will be sure to let you know all about it.