I do, but they are all old production. I have actually never beheld a modern black switch, but I have a suspicion that the older/vintage black springs are not as stiff as newer current production ones. I have a board with newer blacks on it's way to me, and I plan to do a side by side test.
I have made ghetto greens with some of these older black springs and I like them. They are significantly stiffer than normal blues. I am typing on them now in fact.
I also have a pack of 80g originative springs that I am going to drop into the blues on my Phantom when I get a chance. I already tried out a test switch, and those suckers are stiff! I did a side by side with a vintage green (the only green switch I own, one single switch), and blue with vintage black spring, and a blue with 80g spring. The 80g was noticeably stiffer than the other two.
It went: blue with 80g>vintage green>blue with vintage black spring. I plan more tests in the future. I have yet to use anything objective like the nickel test.
EDIT: OP, I have an extra bag of @100 vintage black springs. You can have them for cost of shipping. Just PM me if interested.