I've done quite a bit of reading on the issue of slamfires and I would have to say that the comments about them here are right on point. The issue seems to raise it's head when the cosmoline isn't cleaned out of the firing pin channel, or, when dirt or crud is allowed to accumulate causing the pin to bind. I suppose that a burr or other machining defect could cause a problem, but my pin moves freely as loose as a goose. My practice will be to inspect and/or clean the firing pin regularly. As I was planning to acquire a spare firing pin anyway I will install a Murray's spring pin and put the original aside for the spare. A good part of the problem seems to be folks acquiring the SKS unaware that they need to break down the bolt and remove cosmoline from the fring pin and firing pin channel.
As to negative creep, (the hammer actually moving forward before the break), it isn't necessarily a problem that will cause firing with some jostling or dropping. I have tested my rifle and there is no issue despite negative creep being present. Still, a good thing to check by cocking the gun and dropping it on its butt or smacking.
I can see that like Mausers the SKS will be addicting. Hopefully prices will come back down soon.