Thanks for the link! I skimmed [10], and assume you are referring to figure 7. I think you've read too much into that result.
Starbursts do indeed use angles as part of the rendering algorithm, but for a given subdirectory, you end up comparing lengths just as you would in a flamegraph.
The key difference is that the screen real estate used to render the "icicles" increases linearly with the number of levels with sunbursts, but is constant for flamegraphs. This greatly reduces the "10 icicles, each 1-10 pixels wide" problem that flamegraphs have.
Also, jumping back to baobab, I find linking the directory tree view widget to the sunburst leads to a much more intuitive/obvious set of navigation primitives -- it makes it easy to jump to a parent or sibling of the current view.
As a side effect, they can (and do) put a bar graph on each entry in the tree view, which brings it to "2d position along common aligned scale" which is two levels better than flamegraph or sunburst (3 levels better than sunburst by your reading).
This doesn't help the tree view's usefulness for navigation, but it nicely complements the readability issues with sunbursts (or flamegraphs)