I've fired a Bond Arms 45/410 - and I kinda like it. I also like driving a a 1959 Studebaker Lark.
I keep thinking the derringer could be improved ie. made with better triggers... I'd like to see something like a revamped Mossberg Brownie in .327 mag. ie. flat like a semiauto, reliable and quick like a revolver, and concealable like a derringer. Imagine a stainless 4 shot Brownie in .327mag - or even a Brownie-like 3 shot 45/410.