Using New Outlook on Windows for personal email, calendar, and contact management
Win PC-wise, the Mail that came with Win10 supported Unified InBox. Worked pretty well. Migrated to OL 365 running in "Classic mode" which also worked fine. 2 days ago, found OL Classic had died overnight and would not startup. Still a tbd on that...
Temporarily ran OL 365 in New mode. Got the multiple Favourites inboxes which was an irritation but possibly workable. However, the real bummer came when I discovered there are cross-mail Move-to and Drag-Drop restrictions (eg between Outlook Live and Google). That may be due to default SMTP/POP/MAPI setting, but if not, it is the biggest of show-stoppers.