I have a batch of Cherry MX Blacks from a Nixdorf board for someone's keyboard build, and I was curious to see how they compare to vintage as well as "old" well-used MX Blacks, since I've had multiple batches of each along with some brand new scratchy MX Blacks. Being someone who is very sensitive to scratchy switches, this is something I've done a lot: tinkered with various switch batches and various lubrication materials and methods to get the smoothest result possible, and I frequently compare different switch batches for my own reference.
Visually, Cherry MX Blacks made for Nixdorf keyboards have that semi-translucent milky tops that are a tad more brittle than regular black tops and less brittle than the clear non-Cherry tops from a recent group buy. These translucent tops are a lot less transparent than the recently made non-Cherry tops. They are a tad yellowed, I am guessing from age.
At the same time, the clear tops on the "Nixdorf" switches also vary among themselves: some are more transparent and others are more milky
The spring inside these witches is either silver or faded bronze-gold toned. So far, it seems that the more transparent versions have silver springs while the more opaque have gold. The metal leaf part is faded gold.
Now on to the "feels".
Having read about the legendary smoothness of Nixdorf Blacks, I expected them to be much smoother than vintage and old Blacks. Unfortunately, that is not the case with the batch I have in front of me. Yes, they are
very smooth vs. any brand new and somewhat used switches, but my batch of vintage MX Blacks from WYSE terminal boards that whiskytango took apart was about as smooth. I also have a lot of his "old" MX Blacks (same age, I believe, and from the same boards, but with the more recent small Cherry logo) in front of me as well, and they are also very very smooth. I can't really tell the difference in smoothness trying switches at random from the Nixdorf bag and from the old MX Blacks bag--some are more scratchy and some are butter smooth.
Just like there's some difference between individual "Old" and "Vintage" MX Blacks--some are smoother, some have a bit of gritty friction, some are in-between: same with these Nixdorf switches. Some are buttery smooth and some are a tad more gritty. I believe this is due to where each switch was mounted on a keyboard and how much it was used. In other words, something like an "A" switch should be very smooth where a "print screen" switch would be on the less smoothed out side. I should note that I've also had less-than-smooth "vintage" (large logo) MX Blacks that came with my LZ-GH, and I am convinced that there's a large degree of variation between batches: new and old. So everyone's experience will differ based on what they happen to have.
With that said, these "Nixdorf" MX Blacks are very nice switches, and the translucent cover will be a nice bonus for LED backlighting. Other than that, I don't believe there's a difference in smoothness, batch variation aside (it's equal for every Cherry switch type), between Nixdorf Blacks, "Vintage" Blacks, and well-used "Old" Blacks.
ETA: just took apart all the Nixdorfs I had, and it looks like there are two main batches (but possibly more within--who knows Cherry and their multitude of numbers!). The switches with more transparent tops all have silver-toned springs, and the more opaque switches have a darkened gold-bronze spring. I tried checking if the bottom housings were different between the two types, but they look to be the same. The numbers on the bottom housing were mostly between 103 and 135 for the more transparent tops (though one or two were up to 185), and the numbers on the bottom housings for the more opaque tops were mostly between 135 and 185. I wish I knew what those numbers meant: batch date codes? Factory codes? As for the clear tops themselves, some had the same exact numbers while being of two different opaqueness levels.
Not really relevant to this review: just random thoughts: More
I should also add that I finally got to try a topre keyboard, and topre is much much smoother than the smoothest Cherry switches I've tried. So if these are the smoothest Cherry MX can offer, it seems to be physically limited in design in how smooth it can get, even with proper lubrication. Edited to add after some discussion below: that said, you can still have a very very smooth typing experience with well-lubricated smoothed out Cherry MX.