Regarding this tutorial - this will only create a new profile and default to it, correct? So the old profile stays intact (although somewhat hidden, in that they would have to tell Windows to toggle over to it). This tutorial won't duplicate profiles each day it's run correct? Also - after a few days / weeks (assuming everyone has moved over) - this GPO could be removed correct?
It creates a new profiles and it does not affect the old one at all. Once the new profile has been created the GPO has done its work and the group policy can be removed if you think you are done. Remember that even with a new profile you can still have issues with prompting for wrong certificates and if it does deleting the old Outlook profile and cleaning out accounts and passwords in the Fault on the client may help.