Hey, I just read the errata(UC), and it only seems to effect the double barrelled musket, not the double barrelled pistol. I am very confused as to why you say it requires a standard action to fire both bullet under the equipment section for double barrelled pistols. Shouldn't you be able to do a full round action with all hits with no problem?
Anyways, I enjoyed reading your guide, this is the first time I have ever played pathfinder, and the gunslinger was a class that interested me. FYI, I'm an undine pistolero, who wishes to dual wield and do as much damage as I can!