Super Nova
I wanted a shotgun for the side matches that my IDPA club puts on. I started to order all sorts of parts for my Remington 1100 and convert it over to a tactical shotgun, but the cost was too high ($200 barrel, $80 stock, $45 magazine extension, $40 bases, red dot sight $75 - $300). Anyway, to make a short story long, Friday I bought a Super Nova with the "steady shot" stock (a stock with a pistol grip) and the ghost ring sights. $425 out the door.
The ghost ring sights are great, with them I'm thinking I can do without the red dot sight.
I would guess that it would be just as expensive to go from tactical to bird gun as it was going to be going from bird to tactical. Maybe there is a Mossberg combo gun that would do if you can't have but one gun,,,, but I think a two gun route is the best way to go.