3 bronze keys (never got around to spending those free introductory keys)
325 silver keys
386 gold keys
This is what I have remaining after having spent 218 silver keys and 180 gold keys. In case you're wondering, keys will overflow a stack after 200.
Based on my experience, the current shoulder drop rate is about 10% for silver, 50% for gold. Not sure what the new silver and bronze drop rates are, and they're doubling gold from 50% to 100%. The problem, though, is that the loot table will now be diluted by the introduction (or re-introduction, in the case of Sturdy) of other traits. So the chances of you getting a shoulder is higher, but the chances of you getting a shoulder of the trait that you want is still about the same as before.
I have heard this over and over now but I cannot find the official wording on the gold chest guaranteeing a shoulder piece. Could someone please link it and share with me?