Is this what you are wanting in the first line of your bucket list?
If so, it is already in Dorico 5 Pro - in Engrave mode, select the first notehead in a group of beamed notes, then Properties > Beaming.
My first wanted feature would be the long awaited ties in repeat box.
Second: fixes for condensing, and condensing all held instruments, not only the first.
Third: support for cut-out scores. So that I don’t have to read so many requests for this feature (I suppose I won’t need it much!)
I would agree with these, but of course the decision what to include in Dorico 6 (except for low-hanging, last-minute bugs that come to light) was almost certainly made months ago.
Multiple independently moveable fingerings per note.
Input of any symbol or symbol combination as a fingering.
Simpler handling of octave lines so user can easily angle them as they wish and the ends of the octave lines are the standard ones and not boxed off as shown here:
Custom chord symbol suffixes that can be applied to all roots.
Kerning settings for chord symbol slashes.
Text Frame default positioning settings. I almost always want Top not Center.
Ability to Copy/Paste Text Frames. Additionally be able to do this in a way where they aren’t linked, just like any DTP software.
Layout specific line breaks for Tempo and System Text.
Positioning overrides for whole rests in Condensed staves.
Flow headers that can auto-expand vertically to accommodate text.
Audio export naming controls
In the editor used for Music Symbols, Edit Chord Symbol Component, etc. have some sort of feedback for the user to see the font and size of the selected glyph. Workaround of having to hit Save as Default then view the userlibrary.xml just to see the attributes of a selected glyph is dumb.
Much more control over beaming and ties in syncopations via general options, so one at least doesn’t have to resort to force duration to realize standard groupings: ties to the second-heaviest beat in the measure on the 8th-note level and to every beat on the 16th-note level.
My one wish notationally would be better cautionary accidental management. While the options are legion compared to Finale (even when employing the JW Accidentals plugin), the one thing I’m missing is to consider accidentals in another staff and apply a cautionary if needed. Yes, I can use CMD-R to take other notes into account, but the end result always feels unpredictable, and in any case, it would be great to not have to do that all the time. Thanks.