I have and use both the D7100 and D700. I've just come back from a trip to Sri Lanka which included several wildlife 'safaris/trips'. The results from the D7100 are simply superb, although the D700's sensor is excellent in low light, the fact that I could get 750mm ( or 1000mm equivalent in 1.3 crop mode) at F4 as opposed to 850mm at F8 ( slightly stopped down) utilising the same lens and tc1.7 on the D700 makes it a no brainer. The images imho from the D7100 are simply better than what I get from the D700, as such for wildlife and birds it is now my primary camera. I didn't really notice any problems with the buffer and although I much prefer the build quality of the D700 over the D7100 it handled the conditions of extreme dust and been bumped around the back of a 4x4 with no problems. Its so damned annoying that everything seems a compromise with Nikon, the sensor from the D7100 in a D300/700 body is long overdue but for the time being if i could only use one of them it would have to be the D7100 as for me its image quality overcomes its other shortcomings.