Why? Doesn't Nikon make lenses? OM bodies too hard to find?
If the N75 and F100 are like any of the other later Nikons, the viewfinder screen is too small to manual focus. Especially compared to the OM-1 screen.
The reality is my hands are on my Nikons most of the time. I have a crap load of absolutely stunning Zuiko glass I would like to make use of, especially on my F6.
I got my OM-1 when they first came out and at the time the idea of mounting a Zuiko on a Nikon seemed crazy. However, that looks like a cool bolt-on conversion. Price is not too bad; probably worthwhile to get one and try it out on a lens.