How good are Sabatier knives? Are they used by professional cooks?

Let’s tackle the second part of your question first, since it’s easier for me to answer:
This professional cook uses a Sabatier Chef’s knife at work on a daily basis. Have been for seven-ish years.
A carbon steel K Sabatier, to be more precise. It is my pride and joy. Some of my colleagues have nicknamed it Excalibur at times …
Here’s a gratuitous photo:

That knife is ridiculously easy to maintain scary sharp, and was 80-ish€ a couple years ago. It effortlessly outperforms the multiple hundred Euro ‘fancy’ Japanese knives some of my colleagues rock. Not very forgiving of sloppy maintenance, though. At all. And the fairly thin blade with a not particularly well rounded-over back isn’t the most comfortable I’ve ever used, to be charitable. Less bad than Global knives, but not great.
And now to tackle the first, and more complicated part of the question:
Sabatier isn’t actually a brand name. There’s a variety of companies that make knives of wildly varying quality, some carbon steel, some stainless, of the same general shape under that name.
Some of those are spectacularly good knives for relatively little money, some are utter crap, and most are somewhere inbetween.
Personally, I’d say that carbon steel K-brand Sabatier knives are some of the best culinary knives out there, their stainless ones are allright, but not exceptional, and anything else calling itself Sabatier is a gamble.
All that said: the most important thing about any hand tool, and chef’s knives specifically, is that the blade geometry, handle shape, weight distribution and size need to work for you. Personally. Individually.
You absolutely need to get your hands on an example of that particular model of knife and try it out (at the very least mimicking actual cuts on the store counter) to know whether it works for you. If you’ve been using knives for hours a day for a decade or three, you might become pretty good at figuring out whether a particular model might work for you without actually laying hands on an example — but then, you likely wouldn’t be asking this question…

Wanbasion Black Stainless Steel Knife Set, Sharp Kitchen Knife

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