Maybe this has already been decided, but here goes.
Which is best for all around use, feeding/reloading, plain brass cases or plated ? And, if there's a long-term problem with plated cases, what do I need to look for ?
Here's my opinion, and it's just my opinion. There is no difference between brass & nickle-plated cases as far a feeding or reliability. The pro arguement for plated cases is that they won't tarnish when kept in leather ammo loops on a gun belt, and they're easier to find in the grass. The con arguement is that, over time, with repeated reloading/firing, they become brittle and will split sooner than brass cases.
I like plated cases, but not enough to pay extra for them.
IMHO, the durability advantage of plain brass cases over nickel is purely theoretical. You'll either lose the cases, or the rims will get too torn up by extractors, long before the nickel cases get "brittle".
I haven't tested to see if there's a reliability advantage to nickel cases, but I've noticed that commercial defensive loads are a lot more likely to have nickel-plated cases. Thay may mean the ammo manufacturers think they cycle better, but it may also mean they're trying to make you think you're really getting something special for your money when you're paying 50 cents or more per round.
The nickel cases clean up a lot faster than plain brass, so your tumbling times will be less.
To me, the best thing about nickel cases is that it's a lot easier to tell my fired cases from all the leave-behinds at the range.
I have a couple dozen nickel .38sp cases, and every time I reload them, I find another one or two with split mouths.
Not sure if the same would apply to .45acp or not, since I only reload brass for those.
I have found that the nickel plated split at the case mouth a lot sooner then my brass ones as well.
I just stick with brass if I find a need to buy. But I do not shoot in any matches either. Mine is for my own target practice. The nickel I do reload is form my self-defense ammo that I run through the pistols once a month.
Got me to thinking, since the nickel brass I am shooting is from the SD ammo and loaded usually a little hot, perhaps that is causing them to split sooner because of the initial loading from the factory being hot and more stress on the case?