Not for nothing but it would seem that you can change out mags fairly quickly with some practice.
I can not see the problem with using a Siaga 12 for hunting as long as you can hit what you are aiming at. Is the Saiga the right choice for everyone, no.
Given the OPs original post and intentions for the gun it would seem like a good fit. At the trap field with a red dot I can often hit in the low 20s with the Saiga (which I rarely shoot). With my sporting gun I hit in the high teens (shot about 50-75 rounds a week). #s drop off considerably when going from trap to sporting clays but I have not tried the Saiga at 5 stand yet. May have to do that this week.