Shotgun for home defense is probably the LEAST LIKELY to ever need to reload... Saiga 12 are awesome for having fun or waging urban war/civil unrest/fomenting change or looting liquor stores..
Home Defense? Not really at all, I'd take my 930 SPX over a Saiga any day, in fact if you gave me the Saiga I'd sell it to buy a 930 SPX (or even a 590A1 if not able to get a 930 SPX)...
Changing magazines while a home invader is marauding? Not really tactically feasible... Much more likely to shoot-one-load one or even just go through your 5-8 rounds in your shotgun, maybe pop a few in from your shell carrier/stock soft shell carrier/bandoleer/pocket etc.. But mag changes are for warfighters in warzones, not HD with a shotgun, IMHO.