Which do you default to for someone coming from years of Thunderbird usage? How in-your-face is compact mode toggle in the ootb experience for a fresh install? And sadly how many people are going to be new to Thunderbird these days?

If I got the 'polished' version as part of the normal update cycle I'd be upset that my tight, space-efficient and incredibly responsive productivity app had decided to use a design language that reduces information displayed. The point of email is to communicate information and I now have to interact with the UI more than I did before to get the same amount of information.

The launched version hits the density that Thunderbird has been for about a decade and is what I'd prefer (ie the compact mode might be better for those being upgraded).