You will... wait til the reviews start coming out,
some are already checking this - it's just the information isn't public yet. Further down the line there will be more reports too... it's interesting to observe how many people still haven't gotten their heads around the issue with the 970 yet even
It is improved compared to the 970 as there are some changes, but the fundamental issue is still there. The "tagged on" 2GB of redundant memory is accessed at a slowed speed than the main 6GB.
A reasonable number of users didn't notice the issue on 970... so the same people won't notice it on the 1070 - but some of us find it very easy to notice...
For a single card setup, most people will find the 1070 OK and it will be a good performing card - especially on paper.
It's a slightly more even breakdown than the 970, but a similar fundamental issue is present.
The 1070 should be a 6GB card... the 970 should have been a 3.5GB card.
It's very frustrating that Nvidia are doing this... they would still sell loads if they had set them up correctly. I'm sure plenty of people would have been happy with a 6GB 1070...