Personally, I find the workflow in 3d painting programs rather awkward for making photo textures. I prefer to have all my source images open at the same time in different windows and clone from the photo directly onto the texture template. ZBrush and friends are great for painting freehand or fixing seams, though.

Edit: Yeah, and what MikeJ said. Combine the two, and you have the best of both worlds.

-- I'm not mad at you, just Westphalian.