It's not obvious to me that this is a win for Tornado users.
There's a cost to adding a dependency on Twisted. It's one more thing to download. There's more code to understand when something goes wrong. And so on.
What are the benefits to me as a web programmer? If I understand correctly, my application will work as it did before. If that's true, then Twisted did not add any win for me.
Which has better test coverage and more users than the Tornado stack. Honestly code quality would be the least of my concerns with twisted. If there's a python project where the critical parts can be labeled "mature" then twisted is it.
I criticize twisted for usability and documentation problems. But as the underpinning for something else (with hopefully better usability) it seems perfectly adequate.
There's a cost to adding a dependency on Twisted. It's one more thing to download. There's more code to understand when something goes wrong. And so on.
What are the benefits to me as a web programmer? If I understand correctly, my application will work as it did before. If that's true, then Twisted did not add any win for me.