I figure if I'm going to roll with a tube mag shotgun, it's better to have 14 rounds readily accessible plus one in the tube than to have at most 7 or so.

I would still prefer a Saiga 12 however, over a pump design. I can't argue with 12 round detachable box mags and semi-auto capability. I can run an AK very quickly too, and the difference is negligable between the shotgun and rifles.