Have you successfully resolved the issue with SetBackdropBorderColor in your addon on the PTR server? Also, have you considered exploring the suggestions from the WoW forums, like the changes to SetBackdrop in version 9.0?
I'm not sure if this is asking an actual question or not.
Backdrops are now optional for frames where they used to be rolled into every frame by default.
A frame can get back all the old backdrop functionality by either inheriting the "BackdropTemplate" when it created or for an existing frame you can do something like