However it didn't seem to revert any settings I changed (such as custom keybindings), nor did it replace any of my modified. I also decided to try repairing/verifying with GoG Galaxy. When I wanted to try returning to vanilla.
More than likely not from my own personal tests. So, I have two questions: Will Gog's Verify/Repair return my game to its original vanila state so that I may start again with mods that work with version 1.11? I'm assuming that the reason there's a discrepancy between NMM and Nexus's download history, is probably due to them either being out of date, or you downloaded them manually and NMM didn't process them. My download history at Nexus tells me I've downloaded 9 mods but when I installed a new version of NMM it told me I had 3 (now deactivated). Back then I went mod mad installing quite a few mods.
I'm returning to the Witcher 3 after a break doing other things and haven't played since version 1.04 (I think).