Everyone should carry what they shoot best with. Some states limit the size of the carry gun. Some states make you qualify with the gun you intend to carry.
As for the noise, any good set of muffs with at least a 28dB rating will protect you against the BOOM gun.
Frankly, I agree with you. If your state doesn't have open carry, he'll have a hard time concealing that hogleg.
"I don't know much about guns..." I hear that a lot and frankly, it scares me. A lot of people who have never even shot a gun before are trying to get CWPs. I believe at least a minimum handgun safety course should be required (or taken by exam) before the CWP class can be taken.