Also, for those interested, here's a 100% crop comparison @ISO 3200 of the 70d and the d7100, which everybody's been dubbing the king of APS-C high ISO performance. https://www.dropbox.com/s/xu53htrho7zc4lb/Screen%20Shot%202013-08-04%20at%202.45.22%20PM.png
Having a look around the image, here are my observations:
- 70d's grain looks bigger, but this most likely has to do with resolution and pixel pitch (70d's 4.11µm vs d7100's 3.9µm)
- d7100 exhibits more color noise in the shadows
- 70d is brighter by roughly 1/3 stop
- Both retain detail equally well (although the nikon looks sharper due to more MP and a better lens)
- The nikon is green (surprise surprise)
The point has been made that APS-C sensor tech is most likely reaching a plateau, and I agree. The take-home is that these two cameras are performing equally well, and just about as well as any crop camera is going to perform these days.