Just a few points of clarification: the difference between a full-frame 35mm sensor and a cropped frame is probably greater than the difference between full frame 35mm and MFDB.
MFDB has the advantage of producing slightly crisper images due to its lack of an AA filter, but the 35mm DSLR has significantly better perfomance at high ISO, has greater flexibility, and is, of course, much lighter and less expensive.
However, the D700 compared with a cropped format DSLR like the Canon 50D, is also a rather heavy camera, and in my situation a weight which is exacerbated by a heavy lens such as the Nikkor 14-24/2.8.
Primes are almost always better than zooms, with a few exceptions such as the Nikkor 14-24/2.8 which is as goods as, and sometimes better than a number of wide-angle primes.
However, no matter how good one's prime lens, if it's not the right focal length for the composition, resulting in the need to crop the image in post processing, then its advantage is not only diminished, but the zoom may actually produce better results.