Defense is always good with the overwhelming ability to fire downrange. Yes it just loads like a normal shell might need a different barrel though.
Indeed, though that's more of an offence is the best defence sort of approach. Needless to say, the tournament I'm intending to use the character in frowns upon firearms in general, the Saiga is almost too effective a weapon, in other words. Even with bean-bags loaded it could pretty effectively stop the majority of characters in their tracks.
It could also be a tad cumbersome to use in one hand, I'd assume (edit: Ninja'd me there, interesting to note the tactical sling though.). That's another reason to use the sawn-off, it's not exactly ideal, but it is of a relatively convenient size for one handed use at a pinch. The defensive nature of this character I'm making is heavily dependant on facing the enemy with a riot-shield in hand. I imagine he'll be quite infuriating to fight.
Something else I noticed from a vid I just watched that seemed to feature a non-lethal Saiga, it suffered a jam after three shots. Obviously something like weapon jamming is under my control, but imagining this in a 'real' situation, a double barrel probably can't suffer that sort of malfunction.