I have 3 SXS that I like: A 20" barrel Coach Gun (Stoeger) with a straight grip, the right barrek Cyl, the left ImpCyl, a Stevens 311 "Guard Gun" 18" Cyl barrels, and a Browning SS with 18.25" barrels also Cyl, the Browning also has an extra pistol grip made from a broken stock. The Coach Gun shoots real close to POA at 35 yards with the right barrel, and off the bottle target at the same range with the left barrel, but with most Buck (#1, 4, 00) it patterns well at 25 yards with both-go figure.
The Stevens will put both slugs on the bottle at 20 yards, and not much after that. The Browning will put slugs from both on target at 40 yards but with no predictability as to where, about an 10" group. I use standard length slugs, finding absolutely no advantage in the 3" mags, just more recoil.
Moral of the story: Ok for real up close and personal, but probably better to use Buckshot in doubles, with the Browning(it has ejectors) one can keep up with any other shotgun in continous rate of fire, and with polished chambers in the others (with extractors) very close to it. Just watch some Cowboy Action Matches.
BTW, with the pistol grip looks mean on the Browning, but it is essentially useless beyond 10 feet, and it hurts!
I do love the double look however.