This information is from Robert B and Jim, in response to a question from Tom who contacted me:
I don't own a Pan-Am Brilliante but I asked my friend, Jim, who is a collector and here is his response:
I was really excited to get a Brilliante because it looked just like a 524N in the eBay listing and was way cheaper. It has very similar looking keywork and the one i got has a same design adj. barrel. However, it has a larger bore and slightly different key placements. It plays far worse than any other metal clarinet that I have restored. Worse, I couldn't use my regular mouthpiece. I found an oddball [mouthpiece] that was not usable on any other clarinet but sort of worked on the Brilliante. At least one other collector had the same experience. Take a pass on that one."
Unlike wooden horns with can modified by undercutting tone holes or adding a Chadash barrel or a Moennig barrel, the metal horns has some limitations to them that can restrict improvements to the playability and tone.
However, Tom (who is a senior citizen) and who has one said, "I rather liked it back in the day."