I have 4.8.3 that I got with my D-Lux 4.
What if any work flow changes took place in 5?
I remember somebody requesting the ability to import directly from SD card into current capture folder.
Did that get added?
Yes.
Where can I see a comparison of 4.8.3 vs 5 or the release notes for 5?
Here's an overview over the most important new features, feature comparison between 5 basic and PRO, tutorial videos for 5 etc:
http://www.phaseone.com/5