Looking at benveniste's very informative comments (for which thank you), there isn't much that would be important to me right now, although some things that might be down the road.
- Ergonomics: I have a D70 and D100, similar to the F100 - but I really like the hold and feel of the N90s, even though different.
- 96% vs 92% viewfinder; blah.
- metering feedback; I'm kind of used to my Nikkormats, so any feedback is a bonus.
- aperture stops: this is useful when using AF lenses, but I doubt it applies to AI lenses, and most of mine currently are AI. And for some reason, I dislike G lenses even though I have some; they just seem incomplete!
- I don't have any VR lenses -- yet
- I seldom use S or P mode
the rest is not important to me; and the N90s can autobracket with the data back, which I have
I guess there are some differences that could become important to me down the road, which will keep alive my desire to acquire an F100 with money I don't have. But thus far, I'm encouraged that for me at least, I'm probably not missing too much.