NVIDIA's new DSR is like 4xAA?

Having looked at NVIDIA's official explanation of the new Dynamic Super Resolution feature in the GTX 980 & GTX 970, it seems to me that it amounts to no more than 4xAA achieved by different means, since reducing a 4K (2160) resolution image to 2K (1080) is a 4:1 supersample, same as AA as I understand it. Check out the screenshots at the above link to see what I mean.

So, does it look better than 4xAA? How does the performance hit compare? Maxwell owners let us know.

One thing I like about it is that I can bench my card for 4K using my 2K monitor, so I can know the performance hit in my games before I get a 4K monitor.

Don't know for sure, but I suspect the downsampling is not merely averaging 4 pixels into 1 and instead also uses values of some neighboring pixels.