Thanks, I started typing another reply and, as often happens think I've found my own answer whilst going through it
"Not sure what you mean here. Please elaborate."
Sorry, what I mean is, the whole driver for this upgrade from my POV is because we are backing up a 2012 VM that has de-dupe enabled whereas all our B&R infrastructure is currently 2008 R2.
So, I'm aware that if I wanted to do a guest file recovery of the de-duped 2012 VM then I need a 2012 server (with de-dupe also enabled). In my current scenario that simply means I upgrade my (physical) 2008 B&R server to 2012, enable de-dupe & I'm done.
However, as I want to move to a B&R server VM (for resilience) that I can replicate to our other site, but will still be keeping the repository/proxy server (as 2008 R2) I'm not sure where the Veeam 2012 de-dupe capability is required - on the B&R server to read the backup files, or on the repository server to "serve" the files?
Again, having typed all that out, I think it /has/ to be the B&R server that is required to be 2012/de-dupe enabled as that's the server (for guest file recovery) that is reading the backup files (from the repository server) and offering them up for restore via the appropriate explorer?
I've done plenty of Instant & file restores from Veeam over the few years I've used it, just haven't bumped into a 2012/de-dupe restore yet as we only relatively recently deployed de-dupe here...