I previously used Office Tabs v11 (and also TidyTabs, QTTbar, Clover ... must be a tab junkie), but moved over Groupy and it's working fine for me with Office 365 (apart from minor Excel jumps as per another thread). I use it with Word / Excel / PowerPoint / Outlook / OneNote and all are OK for me.
What was your problem with O365, which OS are you on?
If you really want to go back (and at the moment I wont be
, after cleaning (as above), what type of reinstall of Office Tabs did you do? Can you get the main configuration window to load?