I have a Tromix that has been very reliable, but I have less than 1K through it. As Mike pointed out, 3 gunners go through an insane amount of shells, so he probably knows what he's talking about. The biggest issues I've heard is the comp guys trying to get the straight drop magwell conversions to work properly.
The Saiga-12 forums have all you ever wanted to know and then some about them.
The Saiga-12 forums have all you ever wanted to know and then some about them.