I had read about their tribarrel 410 which was supposed to be the width of a 12 SxS. The article said that several were sold to quail hunters (the 410 is popular with quail hunters - shots generally under 25 yds)

I agree with Daryl that a SxS with 3rd barrel below (drilling style) would make more sense. The 3 SxSxS barrel 28 ga seems wiiide. Of course, that gun could handle very well.

I question the 2 triggers. Is the middle barrel bored skeet and the other barrels bored with progressively tighter chokes?

Unfirtunatelky these guns are very pricy.