Took my first CCW proficiency test with an S&W M28 with a 6-inch barrel. (It was the only pistol I owned at the time, and, yes, it did conceal quite nicely in my Bianchi shoulder rig, while wearing cool and cold weather clothing.) After about 1977, all my proficiency tests were taken with a Colt Combat Commander.
The "waaaay coolest" handgun I have seen brought to a CCW proficiency class was a mint (yes, NIB, zero rounds ever fired from it) Colt Python with a 4 inch barrel that the 20-something year old fellow attending the class had inherited from his grandfather. He also brought some vintage FBI load ammunition in the original boxes. The other fellows in the course did manage to convince him to not shoot the ammo (due to its being so rare and valuable), and gave him .38SPL to use to qualify with. This was after he convinced everybody that he really did want to shoot the Python...even though it was worth north of about $1500. The kid was a natural...after only about two cylinders, his groups double action were silver-dollar size at 7 yards and smaller closer in.