Neither of the following problems with default handling of beams between staves appear to be solvable through Engraver or Layout Options:
On consecutive beam groups, the beams appear to be centered between staves, regardless of the interval. Most other software center the beams between the notes of each group, which is preferable in many situations.
While Dorico handles spacing within each beam group masterfully with the ‘Use optical spacing for beams between staves’ checked, it does not appear to apply enough space between beam groups, especially not in tight situations.
On the subject of beam placement between staves, I asked James, the developer who has worked on beam positioning, to describe the current possibilities, and this is what he says:
The way it currently works is that the beam is centred between the staves if the notes on both staves are all within their stave, as is the case in the file you attached, or if they are all outside (i.e. between) the staves. If however the notes on one stave are within the stave and the notes on the other stave are outside the stave, we will centre between the notes, and then trim the position to ensure it doesn’t go inside the stave if the relevant option is set (though the last step is not quite right at the moment - there is a bug with this which we will fix as soon as we can). This latter behaviour is presumably what is wanted in this case.
I am not aware of such a principle being upheld in published music, nor have I found any reference to it in Gould or any other reference. There are definitely times where automated centering of beams between the staves can be very useful, and it’s great that Dorico can do it, but I don’t see how notes inside/outside the staff is an appropriate blanket prerequisite for the chosen behavior.
I think this behavior should be dictated by a global setting as well as the property to override it. Manual beam re-positioning is already possible, of course, but further options for automatic behavior seems more appropriate for Dorico.