What many including I have discovered about the manual refare done by the CSR however is that the sponsored upgrade, which if done originally on the web by the owner requires no further authorization (i.e., an airport visit to sign the bluey in person) suddenly becomes "unauthorized" when the CSR does the refare on the phone. Not to alarm you, but you might not discover this until you try to do OLCI 24 hours out, when it will state "upgrade not authorized", even though the upgrade is indeed properly reserved and confirmed and shows as such on the web. There seems to be no way to determine the authorization status of the sponsorship on the web. What then happens when you get to the airport can be unpredictable, and is a risk if the original u/g owner is not also present.

For this reason I've stopped refaring tickets with sponsored upgrades unless the difference is huge. Of course, if you're traveling with the sponsor, it doesn't matter.