So, I asked around and others were able to upgrade their lines to 2GB and keep the discount. We didn't end up doing it at the time, but just tried now.
New Unlimited Plan from Big Red?
I called up Loyalty and asked if I could upgrade a line, downgrade to 2GB and keep the discount. They said no dice on the discount, thus I can't really do it. That's $480 over the 24 month period, may as well keep unlimited and pay full retail.
Has anyone else tried it lately?