Sorry let me clarify:
There really isn’t any hard evidence the last partition of 512mb will be any slower than the first 3.5gb in real world performance usage scenarios.
As far as tech specs yes the details are known, but there is no data yet on whether the bandwidth difference will actually affect performance. It is pretty clear it will have some effect but I highly doubt it will be anything noticeable. It is easy to see how all came about though, since the 970 does have a total of 224 gb/s when added together. It’s obviously not the same as the 980, but I can see how might have slipped by on launch.
Anyways I have an ASUS GTX Strix 980 and absolutely love it, beast of a card. I personally wouldn’t let stop me from buying the 970 if I was looking to get a new video card. It doesn’t change the fact that the 970 is one of the best performance per dollar video cards on the market. I would still recommend it to anyone without hesitation. 