The 970 is fine. Less CUDA cores is irrelevant.
For Premiere Pro editors the most significant changes are the fewer CUDA cores compared to Kepler and the memory bus of only 256 bits.
However, next to the improvements mentioned above (ROPS, L2 cache, etc.), the much higher clock speed of the GPU can make the GM204
a worthy successor of the 700 range of cards.
and about the problems with the Element 3D V2?
I updated my programs for 2015 and not yet support for GTX 970