OK..... sorry for the delay.
Reporting back. Performed an in place upgrade / repair on my Windows 8.1 Pro 64 bit computer and everything went as expected, actually better than expected as I was having some trouble with the native "Photos" app opening and then promptly closing and the in place upgrade / repair seems to have had the effect of actually fixing that small issue.
Now with respect to the location of user profiles. I need to explain that I have nothing on my C:\ drive except my Operating System, however..... all the data structure remains the same as it would with a normal install.
C:\Users is still there
C:\Users\Randy is still there
All of the sub-folders in C:\Users and C:\Users\Randy are still there
Just like
C:\Program Files is still there
C:\Program Files (x86) is still there.
What I did was create the identical data structure on D:\
So now
C:\Users\Randy\Desktop (while still present) has been moved to D:\Users\Randy\Desktop
same with C:\Users\Randy\Documents and so on and so forth.
And when I install a program I just change the install path from C:\blah blah to D:\blah blah
In other words
I used this method of moving the sub-folders under C:\Users\Randy (more or less).
So I can only surmise that if you used the same method, then an in place upgrade / repair will likely work for you as well.
And another positive outcome which was kinda unexpected, was that I didn't have to repoint anything again. The locations and their references remained intact.
Overall very happy with the outcome. Kinda reluctant to put my image back in place now.
Regards
Randy