One word: Excellent!
Love the new GUI choices you made. They make total sense.
Question/suggestion: the quick search has a number of fields selected by default, it would be nice if I could change these defaults (e.g. I have no use for searching on the file path). I reckon this is already on the list, if not, consider this a suggestion

P.S. Yes, to me it would make sense to switch to the search/filter/browse/collection tab to match the current contact sheet content. But this may not work for all, so perhaps implementing this as an option is best?