Ok, I've done it now, my card still works fine and hasn't downclocked or anything stupid like that.
@newtekie1 @erocker Note that the updater did actually lock up the PC solid the first time while it was scanning, forcing the reset button to be pressed. Ok the second time. Didn't do this previous times when it scanned.
First off W1z, apologies. While I remembered to get a GPU-Z screenshot before updating, I forgot to save the BIOS <smh>. Anyway, I found one with the same version number in the TPU GPU database, so have included it in the attached zip file for your convenience. Hopefully it's identical to what used to be in my card. Note that the TPU BIOS and my updated one do have different MD5 checksums, as you would expect. The GPU-Z screens look the same before and after.
For reference, this is my card:
https://www.techpowerup.com/gpudb/b3621/zotac-gtx-1080-amp-exteme
@eidairaman1 feel free to wag that finger for forgetting to save the BIOS first.