Gulag,
You want to preserve the workflow which starts with your own tailored Nikon in-camera profile and Jpeg, which helps you with shooting.
There is no reason why Phase One's software or Adobe's in fact, should be *best* to help you with a Nikon workflow. In fact, Nikon's software is the one tailored for Nikon cameras and the one to be employed when one wishes to reproduce on the computer side all the quirks of the Nikon in-camera processing.
Your most appropriate workflow would be via the Nikon raw conversion software, which should be able to recognize your personal edited in-camera picture profile. I think even the free Nikon View can do what you want, and export Tiffs. C1 just renders the way its authors decided to do things, which happens to suit many of their customers, while Adobe go to some pains to imitate the stock Nikon or Canon profiles, but I don't think they will recognize and apply your own embedded picture profile - the one you use to create the in-camera Jpeg that is to your personal liking.
It may take some work to configure the Nikon software to apply your picture profile, either it picks it up from the file or you'll have to bring it across to the computer with the picture profile utility or recreate it on the computer with Nikon's picture profile editor.
A question on a Nikon forum should elicit an answer from a real Nikon software expert. Some of the people above who have schooled you on postprocessing are associated with Phase, and it is only natural that they should view the world through the prism of the software which they use daily. They are genuinely helpful, their advice is good, but it is more intended for people who look at a C1 screen with a tethered camera running C1, with a view to using the same C1 color for retouch, than it is for someone looking at the screen on the back of a Nikon to make shooting decisions. If you really want to shoot what you see on a preview based on in-camera picture profiles, the obvious way to get what you want is to stay with the Nikon software.
If I may use an analogy, the advice you're being given is like being told how to filter Kodachrome to try and make it look a bit more like Fujichrome. While it might have been possible to do this, it sounds more logical to just try and stay with the brand that has the look you want.
Edmund
PS. The problem with all these look emulations is that the "signature" of a look is often not in the core zones of the images. The emulsion or look shows off its personality most strongly in the falloff behavior, the shadow and highlight tints, eg. the face shadows or where the spaces between leaves go dark or show the sun, and these limit behaviors are really hard to replicate, be it in picking up the signature of an emulsion or just that of a digital camera.