I never thought of myself as a "power user". But it must be so, since I rescue public domain books and use Sigil, Calibre and Notepad++ as my primary tools.
I only use book view for splitting chapters and proofing, while code view is used for all other editing. So WYSIWYG is not very important to me unless it is needed to proof.
You mentioned that you had "marked a number of issues on the issue tracker as Milestone-0.5". Which ones were they? I have a particular interest in the "zoom" enhancement (issue #637). Any idea when that might show up?.
Regards - John