Whether its a upgrade or downgrade can be argued. I think the OP is not getting screwed getting a new replacement.
The reference 5870's all have voltage adjustment. This is left out of almost all non reference. They use cheaper, less expensive voltage IC's . Most times reference cards are over engineered, and area's that can be scaled back and remain in tolerances are done to save money in non-reference.
Reference 5870's had those nifty back-plates.
http://forums.techpowerup.com/showthread.php?t=105483