I love my Saiga-12, there's nothing it won't do. There are after market parts that will fix all the issues you mentioned, relatively inexpensively.
A gunfixers gun plug will give you a total of four gas settings, and you can adjust it by hand.. much easier than the factory plug. I also picked up a Go-Gun twister puck... I needed a U.S. part anyway. Don't know if it helps, but it does keep it clean. I also put an AK-builder choke adapter on it, so now you can use any Winchester thread choke. I had mine out hunting Grouse and shooting skeet.... zero malfunctions, and I couldn't miss. It's my all around bird, Turkey, deer/slug, zombie gun.