Is it worth buying GTX 970?

I’ve got Gtx 580 2GB at the moment. I want to buy a new card for better render times in Cycles.

Is it worth to buy GTX 970 4GB ? Are there any good benchmarks in cycles?

Any thoughts?

Is it possible to “connect” (SLI or whatever it’s called) these two cards so I got more CUDA in Cycles = faster render time and more ram?

Since there isn’t a massive performance increase from going to a 970 over what you have it might be a good idea to wait until next gen GPU’s are released because it looks like new cards from AMD and Nvidia will be released in mid 2016.