If you're "painting the walls" then you're clearly doing something wrong. I have killed a lot of fairly large animals (sheep, goats, pigs, cattle, deer and horses) with a .410 shotgun, and have never painted anything. It just makes a neat round hole, with no mess. And there's the added advantage over a pistol that you have a bit of extra reach, should the animal not be too keen on you being up close.
It's noticeable that the knackermen who drive the fallen stock wagons around here all have a shotgun in the vehicle for HD, not a pistol.
The only time I can see a pistol being an advantage is if you're in a situation where it is necessary to carry it with you on your person in addition to your main firearm. But I should say those situations are extremely few and far between.
I have no problem with anyone owning a pistol. I should think they're a lot of fun. But I do question the usefulness of a pistol for HD.