Thanks for your quick responses. I was hoping it would work, and over time I hoped there would be some certainty that the same utility works for GP 2013. SharePoint 2010 is good and I am seeing interest in SharePoint 2013, so that will be a welcome option in the next couple months. Based on Derek's response I will probably try it since it didn't ruin anything. I assume the risk of it not working is needing to manually setup security for the custom SharePoint Business Portal roles. It will be an upgrade, so with any luck it will retain that, but the upgrade document reads that even during an upgrade the security will need to be reset.
Thanks again.