We are migrating to an html-based workflow using Prince for most of our books and so far it's working great. However the lack of non-rectangular floats is a real limiting factor and for some of our artwork-heavy books simply means Prince isn't an option.
Do you have any timeline for when CSS Shapes might be implemented?
Oh well, that's bad news, but thanks for the reply anyway.
Regarding the hanging punctuation question, did you have a specific library in mind? If you post a link I could investigate whether it works or could be made to work in Prince.