Well, what I have just done today is to make image backups of my entire C drive and F drive (dedicated 300GB velociraptor) onto a WD MyPassport 500GB USB drive.
You make my point here when I read where you are backing up your entire drives..."C" and "F"
hence the term "saving baby and bathwater" by saving C drive (with registry keys) and F drive (with FSX). You did provide that much "detail" however,
And again I say, what is desired, is a backup of the FSX drive and a set of exported FSX-specific Registry keys to append/add to the current registry...(something that doesn't require backing up and restoring the entire C drive and thus the entire registry)
Now I would think backing up just the registry albeit inclusive of ALL installed programs
(FSX and non FSX ) would be a tad bit less drastic and involved then backing up the entire "C"
in addition to and image of your "F". If FSX were installed on the "C" where all the registry keys are then things would be simpler to restore, Yes?
I don't think anyone has a "workaround" to this conundrum.....