The current issue of Shooting Times Personal Defense magazine has Mossberg's newest shotgun on the cover.
 
The Maverick HS 12 Over/Under tactical shotgun.  Sorry I couldn't find a photo to put here.
 
I think it's a great idea.  The Only down side I see and they mention it, is that it has Extractors, Not ejectors to remove empty shells.
For those of you not familiar with breakopen shotguns, Ejectors will pop the empties Out over your shoulder. 
Extractors, just lift the empties out far enough that you can pluck them out.  In a "fighting" shotgun, this will lengthen your time to reload.
Stated reason for extractors is that Ejectors will add cost (and more parts) to the gun.
 
It's OverAll Length is just under 36".  It has rails on top and under the barrels.
 
If I didn't already have a similar gun, I'd give this some thought for the Wife if it came in 20 ga.
 
Here's Hers, Browning Citori 20 ga open choke, with Smith & Wesson Model 13HB 357 wearing CTC laser grips.
 

 

A tactical O/U?   Unbelievable.  No, not unbelievable, but absurd.  Next, we'll doubtless have the opportunity to buy a tactical rolling block, which will only open the floodgates to dozens of tactical muzzle loaders!  Weaver rails, collapsible stocks, light/laser combos, ACOG sights, and Kevlar ramrods!

Hey T G,
 
Remember the Wells Fargo stage guards used S/S sawed off shotguns.  The only difference with this is that it's up/down.
 
Did you watch the movies "StageCoach"?  Both Versions, old and new.  They used the Assault Rifle of the West, a Lever action
Winchester.
 
With a single trigger O/U or S/S you get a really Fast second shot.
 
Don't forget the "Battle of Abobe Wells", 28 buffalo Hunter fought off at least 700 to 1,000 indians and won the day.
 
Also, a single shot buffalo hunter got the LONGEST Recorded single shot kill on a Hostile at 1,200+ yards, measured distance.
 
 
 

Here's a "Coach gun"
http://www.stoegerindustries.com/firearms/stoeger_coach_guns.php

Here's a "Coach gun"
http://www.stoegerindustries.com/firearms/stoeger_coach_guns.php

Looks like they have 20" barrel OAL 36" O/U's here too.