I directly download the beta when I saw that it supports Windows Hello with the browsers extensions, this is great !
Here is my feedback for my quick test :
It's impossible to change the keyboard shortcut on the Firefox extension
It would be cool to add an option to automatically launch Windows Hello when the extension is opened. It takes time and is simply annoying to go on the extension and click the icon to launch Windows Hello.
I'll switch to the beta when the Webdav synchronisation will be available !