Hi Fred,
This issue (of having to redo your customizations) comes up at every Power Users Group and in random conversation with Alan whenever a new TBC version releases.
As an encouragement, your request ("I want to import a tab from a previous TBC ribbon") is already on our near-term TML roadmap. UI customization ease-of-use is our first focus for TMLs.
So hopefully between Revenant and Rockpile, you'll have to find something new you always "like to do" when a new release comes along...
Quan
Revenant Solutions - Independent TML Development - Build. Share. Grow.