I did post "requirement" but it was early this am I should have quoted with greater accuracy from the release notes.
To clarify :
Quote
If you previously have installed versions of Capture One 4 on your computer we recommend
that you should start by uninstalling these before you install this version of Capture One 4.
Unquote
I did this and was not required to re-enter my key. I suspect Baxter you may find that rather than copy over the existing version you now have both available. But I may be wrong it has happened before
I am told stability has improved. I have experienced some unexpected close downs (on Mac) and memory hogging. Early days to se an improvement it was very intermittent. The tethering is very welcome for the MFDB.