There is a "tiny-not-a-lot-of-explanation" sk113615 about changes made between R77.x and R80.x.
And before you say Tim Hall - there was not a lot in the new book
Problem is that there are no automated means to control number of versions you keep so it keeps growing indefinitely (unless you remember to do manual purge) and also you cannot turn it off even if you wanted to. Due to the complexity of the network (MDS with many CMAs plus couple of VSX clusters and VSes stretching over multiple CMAs) I'd rather rely on good old MDS backup than revisions.
And now we have hit some wall where purge on MDS simply fails - it sits at stage 3/3 forever and eventually gets "server restart" error
I will raise an SR but would be great to have a bit more insight of R80 revision management / troubleshooting
I also wonder how much this will impact MDS backup size (as it has been growing like crazy)