First of all, I’d like to say thank you to the Dorico team for the great update. It’s always impressive to see how much work they put into the application and the well thought-out features they come up with. The next few weeks I’ll probably be busy with diving into all of these.
Nonetheless, here are two things I noticed after starting Dorico 6 for the first time (on Windows). 
The first thing I immediately noticed was the enlarged menu bar. It now takes more vertical space as the “regular” menu bar of other Windows applications due to a larger font and increased padding space around the items. Since the menu bar is light gray in contrast to the rest of the GUI, it is quite prominent to my eyes and somewhat distracting. Would it be possible to reduce the size to the regular height again?
Another minor thing is the clipped German text in the new View toolbar menu:
Because of the long text, the last word “anzeigen” doesn’t fit into the display area. “Registerkarten” (tabs) also sounds quite formal and clumsy to me. I’d just replace it with “Reiter” which shortens the menu entry but would probably require rewording at other places of the application and the documentation as well.