I am a Leaf Aptus shooter and own a Nikon D70 as a play camera. I am thinking of getting a better dslr as just a back up and maybe use it for high ISO from time to time. I am thinking either Canon 5DII or Nikon D700. I know they will not match the quality of my aptus 75, but any real differences between Canon and Nikon? I like the idea of the video on the 5dII but I already own a 18mm - 35mm ED and 35-70mm 2.8 lens.