I did it, and I guess it worked.
There were a few discrepencies between the two directories though:
C : version:
Profil : C:\Users\ALAIN\AppData\Roaming\Opera Software\Opera Stable
Cache : C:\Users\ALAIN\AppData\Local\Opera Software\Opera Stable
portable, D : version:
Profil : D:_Programmes persos\Opera Portable\profile\data
Cache : D:_Programmes persos\Opera Portable\profile\data
Though that was checked, the portable version did not import the favorites from the C : vcersion
C : had a Certificate Revocation Info directory when D : had a CertificateRevocation directory, and C : had a Media Cache directory which wasn't in the D : directory
Anyway now I guess I'll just unsinstall the C : version (which is the only one listed in the Configuration Panel).
I am very glad you bothered to help me along on this. I'd think there should be some thread somewhere (unless there's one already?) explaining how to move your current Opera to another drive, the way you kindly explained for me just hereabove.
Thanks again!