Now that Sandisk have released their 95 MB/s cards (such as the Extreme Pro SDSDXPA-008G-A75 8 GB Secure Digital High Capacity (SDHC))I would be interested in a validation of the data rate you extrapolated on the graph for the "Future Card UHS-?". It looks like the future is here at very attractive prices!
I just ordered myself a couple of the cards since the price was the same as their 45 MB/s version (which seems to be getting discontinued). I paid $32 for the 8GB version. The D7000 specs appear to support the full UHS-I speeds, and the mainline cards appear to converging to that same speed rating.
For those of us wanting the quickest clearing of the buffer (and the subsequent ability to keep shooting), this is an important test and I hope you keep updating it as newer (and faster) cards appear on the scene. Your methods seem to reflect real-world conditions and I appreciate seeing the graphical results.
Any test method is subject to a lot of variables -- but as long as you keep doing the same thing when you run YOUR test, we should have comparable results with the different cards. The graph appears to be a logarithmic curve, which would be expected for this type of process -- diminishing returns as cards get faster -- so I'm very interested to see if the 95 MB/s cards do perform as you expected, and give us the ultimate performance that the D7000 is capable of.
Also, I was trying to replicate your results and noted that having long exposure NR turned on or off does have an impact on the R-xx value -- with it on, I had a smaller R number. It probably doesn't matter for most shooting, of course, but the camera thinks so!
With my current card (Sandisk Ultra Class 6, 20MB/s rated) I get 9s with your test.