I think it's a terrible idea. To invest any time or money into this "build" for home defense situations is borderline absurd. With so many other practical platforms out there, why would you ever want to limit yourself to a SxS shotgun?
If you were in a situation where it's the only firearm you're ever going to own, then you'll obviouly make do with it and live with the limitations of your choice.
So, you're looking for rock solid reliability and ease of use under high stress situations? Buy yourself a Glock and don't look back. If you "need" to have a shotgun then get a pump - any pump at all would be far superior.
At the end of the day, you have to answer to your family. If you sincerely believe you're adequately protecting your life and their's with a SxS shotgun, then I highly doubt we're going to convince you otherwise.
Best of luck to you. I hope you're never put into a situation where you're going to learn from making a life threatening mistake.
And...
So... do you two even have a restricted license or own a Glock? From looking into the OP's nothing indicates that he has a RPAL ...and of all handguns, only experienced shooters can really score with a Glock. You are well spoken but in order not to come off like a "Internet tough guy" get some facts together first. A handgun has its thing in carry and close up defense if you're not at home... A shotgun out to 50 yds does everything a handgun can,but better...above 50 yds a rifle does anything better than the two previous together. The OP asked for home defense...
As others stated, with Canadian law you're in trouble anyway if they find you must have kept it loaded ( or worse used a restricted ). The SxS will do against 5 intruders in a room...the first goes splat, and no one else wants to die next. This isn't about zombie apocalypse or internet games here. And if you have multiple armed attackers, determined to kill you and your family,even over cost of their own life...get another job. Biker leader,mobster or drug lord was a bad choice.

As for loading in the dark under stress...yah, the pump and the card,eh? I got a stock sock on my SxS,you pull two out,feed two in without fumbling them two around,with family protection in mind, because even my ( not remotely interested in firearms ) wife can handle that.
And yes...the 590 is superior, even without bajonett , if you have to use it as a club, you won't bend it. And it has the safety where it should be contrary to the 870. Both are outdated anyway ( have both )...my UTS is shorter and holds twice the amount of rounds.
Still would use the SxS for HD...if i'm going into dreamworld, well...I can mow everything down with a M2.
CG