Z-Michigan,
I see your point about velocities. I personally think that 000 buckshot, at ten feet, from even a short barrelled gun will penetrate thick clothing (but for me it doesn't matter since I only carry it in summer). That is just a matter of opinion though since I have no Chrono data to back it up, and haven't done any tests on it. I'm sure you are correct that the velocities will be significatly lower than the ammo manufacturers state due to short barrels, and I tip my hat to you. The nice thing though is that several ammo companies are making 410 shells specifically for short barrelled revolvers with the success of the Judge. I imagine that will continue with the new S&W Govenor coming out this year. I have no plans to pick up either gun myself. The Bond Arms derringers are well made, and a fun novelty to own. I do prefer harder hitting loads like the .357 in general. I may pick up a Ruger LCR in .357. Who wants to wear the same clothes every day, right?
I have patterned the 410 at ten feet. The #4 buckshot had about a 10" spread and the 000 buckshot had about a 4.5 inch spread. That's why I keep one of each loaded. I figure the #4 buckshot to increase the initial shock, and 000 if you really need a heavier hit for follow up.
I'm not going to say it's the best carry option in the world, I'm just going to say it is an option.
Granted, it may not be the best carry option