Although the Red Rectangle Word citation dialog is good and quick, I really appreciate that you left the "classic" GUI behind as well. That is one reason I won't consider Papers (which only has the "quick dialog"). I find that in plenty of cases I can't remember the name of an author but "I know" visually where the author should be in a sorted list, so the "Classic" view is essential. I mention this in case you are tempted to deprecate the "classic" view.
Also, is there an option to change the default mode ("Classic" vs "Quick"?). If not, I would ask to make that available.

Thanks,
-ALex