Raw capture buffer in the D7200 was improved quite a significant amount over what the D7100 can shoot. D7200's sensor is just a bit better when raw images are deliberately underexposed and then adjusted in software later. There has been a NEW firmware update for the D7100, which is supposed to reduce the banding that it is known for on severely under-exposed images which are later adjusted in software, but I have not heard how well that firmware update for the D7100 actually works from real-live people...so...
Black Friday might have some added $100 off deals on D7100's; cgw keeps pretty good tabs on prices, but he's located in Canada. Nikon has been doing a lot of discounting on its older models, and has trained its buyers to look for deals. I think we'll see some D7100 deals this Thanksgiving season, for sure.
This whole deliberately underexpose in the field then "lift" the images later in software deal has become more and more an accepted way to get to higher ISO levels, especially for users of Sony- and Toshiba-sensored d-slr cameras over the past couple years, because the sensors used in those cameras can create image files that look pretty good when that is done; if you want to literally SEE, with your own eyes, how that works, check out the dPreview web site's review of the Nikon D7200. They are calling this trait "ISO invariance", and they have sample images from multiple cameras, under-exposed by four and five stops, and you can compare the results that different cameras/sensors can achieve.
The sensor in the D7200 is probably the most ISO-invariant sensor they've ever tested--which is a very good thing.