This isn't a direct response, but you can check out my threadhttp://www.tomshardware.com/forum/369525-33-choose-radeon-cards
Where i reference that card as well asking a question.
Supernova gives some assistance.
Again, doesn't directly answer your question, but it does address 'What's the catch? Why was it cheaper than most of the 7850s on newegg, let alone the other 7870s?' a little. I had/have the same kinda question :P
But to break it down into a sentence - That was a great deal. the 7870 should trump all of those 7850's in performance. (I have NO direct experience with the card, for the record)