If you rarely use film then I would say D2X. Knowing fast action is a major part of what you do then recognise that the D2X best quality is in the ISO100-200 range. If you are happy with that then you cannot go wrong. If I had still been using 35mm film when I got my X then that would have been the end of it for me.
Duncans comment on pricing has put me right off getting a roll of 120 to put through one of my other cameras.
Resetting up my darkroom would mean loosing my workshop.
I see you now have a D70s, and Foxy who has used his fathers D70, is best for commenting on image quality between the two to help in the decision making process.
Don