seems swapping a 970 (sell on ebay) for one of these cards is a zero cost transaction with about 25-35% performance gain.
The 1070 from nvidia is priced less favourably than the 970 was at launch. So that upgrade path is much harder to justify.
Just bear in mind tho amd cards tend to not overclock very well, the 25-35% gain is at "stock" clocks, and they suffer in dx11 and older games. So the most likely outcome for me at the moment is I keep my 970 for another year.
Edited by Chrysalis (Mon 06-Jun-16 13:36:17)