I've been toying with two-pass vertical spacing. Pretty neat, and
exactly what I need. A couple questions:
1) Is it *supposed* to force each system onto a separate page? That
seems to be what it's doing: splitting pages with multiple systems. I'd
be OK with this, aside from the smaller systems filled with tons of
white space. Unfortunately, after giving systems their own pages, a
vertical respacing isn't performed on them. In short, only pages that
could fit one system anyway are properly respaced.
This is almost certainly because the height-estimation routines are overestimating the height of the systems prior to page breaking on the second pass. Can you try it (perhaps just the first couple of pages) with annotate-spacing = ##t to check? If the Y-extent-estimate interval is much larger than the Y-extent interval, this is the problem.
Also, what version are you using?