I can see that F# still does not support GADTs. Did you find it a serious limitation?
Depends on what you're trying to do. I've never found it to be a limitation but I don't do anything terribly intricate. Just web dev for work, and I wrote a toy language parser and type inferencer in it. There are maybe three lines of code that GADTs might have let me avoid casting in the type inferencer, but oh well. Different use cases that use GADTs to a greater extent, of course, you might miss them. What is your use case, and how much are you reliant on GADTs in your existing daily life?
We use it in production at Olo, and I used it in production at my last company.
Since learning F#, languages where if statements aren't expressions and that don't have option types feel broken to me =)