b_e-n, thank you very much. That is kind of thing I did to tweak the Dorico slurs and achieved much better results.
In my opinion, your final example of the cross staff slurs is excellent, but does suffer from the extreme arching that one sees in a lot of computer engraving now, even from the best publishers like Henle and Baerentreiter. The best plate engraving of the past, for example, that by the same two publishers, avoided this because over-arched slurs stand out too much and take up too much of the empty space on the page in a way that impedes reading. And it is less visually pleasing because the slurs don’t seem to track the path of the notes as well.
In any case, I found such necessary adjustments to slurs to be harder in Dorico than Finale. Ironically, it seemed that the higher degree of control over the motion of the control points in Dorico gave too much opportunity to misshape the slurs to create unintended bulges etc. With Finale the user is somehow protected from this, which makes shaping the slurs much easier. Perhaps having two levels of control over the slurs, fine and less fine, would be helpful.