They are interesting knives if you want to understand how the Japanese, the German and the Britons have developed their knives. The Sabatier Nogent was the standard at the end of the 19th century, and has been adopted by all makers in the world, changing it little by little to adapt it to the local habits and techniques. See a Henckels / Zwilling from 1910 and you would hardly tell the difference with a French knife.
I like using them for their agility, and for sentimental reasons as well. Half of my family is French, have travelled a lot in France at a time where our NOS were very common. For the same reason my pepper mill is a Peugeot. If I had the place and money I bought a restored Pleyel or Érard grand.
Availability of NOS fluctuates a lot. Besides, there's a crazy market of used vintages. Almost all fllee markets of France and Navarra have been ransacked by clever Californian salesmen who wanted us to believe modern steel is inferior.
It is not. Especially with knives from the twenties, you may encounter crazy moving clustering carbides, due to some impurity. Not just with Sabs: Germans as well — they are all from the same German steel from Swedish ore. I don't know if the ore is to blame or something with Krupp's production process. Expect it to happen with one out of ten vintages. If it appears at the edge, you may sharpen it away. No fun, but doable. If it is 1cm deaper — 3/8" — it will cause breakage, and the knife is lost.
I do use the Sabs in my humble home kitchen. Even the 25cm, when I feel that a hard steel is at risk. E.g. with almost frozen meat. My butcher keeps everything at 2°C — 35.6°F. Sometimes it's a bit close.
In general I have a rotation, how crazy it may sound: I use a Misono for a few days, then a Herder, then a Sab and a lot more.
Is a NOS Sab a serious option for someone looking for a good carbon chef's? I'm not sure. There are technically better knives, sometimes for less money. I got at Amazon an evidently displaced 210 carbon by Kanetsune — a brand, no maker — for €55, here in Europe, including VAT. It was unsharpened — well it got a chisel grind — and it took little time to turn it into one of my best 210.
I can't rationally advice knives that so often come with serious flaws as the Sab NOS. Bends, warps, crazy edges, and with the Nogents the moving carbide risk.
You,
@HappyamateurDK and I all bought within less than three weeks the same 23 full tang, and got different knives.
Sadly, Japanese makers of affordable yo-gyutos all went into CNC production, instead of grinding by hand. Twenty years ago a Misono Dragon came nail flexing out of the box. Now it is about twice as thick behind the edge. It takes a few hours to correct it without powered tools.
An alternative is in Japanese NOS of thirty, forty years ago. JNS has them from time to time. They were hand-ground, really light and thin, even the larger sizes, and Maksim gives them a last sharpening before sending. Of course, a forty years old handle won't look like new. But nothing dramatic. Good prices, but small stocks. Just a few of them, so act in time.
No, no passaround. Makes little sense with knives that require a bit of care. I've participated in a few passarounds and more often than not the edge came run-down after a few predecessors. Rock-chop with a Sab on a poly board, or even better, apply some walking, and it requires at least a touching-up. They get crazy sharp but should be handled with some elementary care.