since version 1, sibelius has been missing an important parameter for the spacing - after dotted values, there is always not enough space between the dot and the next note. Sometimes it even happens that the next note is nearer to the dot, than the note to which the dot belongs.
Adding a "space after dot" to the note spacing rule parameters (or to the house style under "accidentals and dots") would improve this situation.
There is already a spacing rule for "noteheads and dots". I can see the advantage of having a separate rule for dots that does not affect spacing after noteheads, but it might be tricky to separate the 2 rules and still maintain existing behavior.
I would also vote for a note spacing rule to spacing after Special Barlines that are not at the start or end of a bar. Adding a barline to the middle of a bar currently allocates no space, and requires a lot of dragging of notes to make the spacing work, especially when there are multiple staves.
I don't see much the logic behind the "noteheads and dots" rule, as the practical result is that dots are often too near the noteheads. Or do you mean that it's hard to separate this rule into 2 rules because of the internal way the spacing is calculated?
Yes, space around barlines can also be improved - also implementing the behavior of your "respace clef change" plugin would be the best, as sibelius has always left a very strange gap before barlines since version 1.