Mick - I have employed two D700 bodies in doing a lot of sports photography, and now, use two D800 bodies. Frankly, I find the D800 better in all cases to date. The ability to retain and then dig out in PP, shadow detail with the greater dynamic range has been very pleasing. I have been shooting some football this fall, and of greater difficulty, volleyball. I also shot a few photos of a play the other night, when I was in a rush to get back to a volleyball game -- don't ask me why a high school scheduled both events in the same school on the same night! I'm adding a couple of photos here. I'm not demeaning the D700 -- it was my "prince of darkness" for several years. I just like the D800 results better and am soon selling two D700 bodies.
The theater shots are at ISO 1600. Volleyball at 3200. I shoot at 6400 in darker gyms, but this one is lit pretty well.