You know, I find it funny because I bought the D100 in early September, and then I heard some good things about the S2 Pro, so luckily I have a good relationship with a local camera store and they let me borrow an S2 Pro for 2 days. Prior to that, however, whenever I posted questions about people's experiences with the D100 vs the S2 - on various forums - all I got was scolded, plenty of sarcasms, etc. Well, after trying that camera, I came to the conclusion that I had to have that one also. So after figuring out which family member I could sell in the process, I bought the S2.
I don't like using the name "Fuji," because I look at the S2 Pro as a Nikon product that Fuji happened to tinker with. That said, here is what I noticed:
1. Color Saturation and overall balance I find superior out of the camera in comparison with the D100 out of the camera. Now granted, most photos can be made to look picture quality using PS-7 or other higher end image editors, but there are just some situations when you want a photo to come right out of a camera that half-assed represented the picture you took...'ya know what I mean Vern!!!
2. The Flash issue - no contest here. I use my SB-28, my Metz 54 MZ-3, and my Sunpak PZ4000AF and the PZ5000AF - all Nikon dedicated of course - with superb results on the S2 Pro. Not so with the D100, and I hate the fact that I had to go out and buy an SB-80DX and SB-50DX for the D100 alone - although they also work superbly on the S2 Pro and other Nikon units.
Love both cameras, bot in keeping in line with this particular thread, the flash scenario really sucks on the D100.
But as photographers we make do and I am doing what I can to learn as much as possible about the D100 and how to offset perceived problems, etc.
And before I forget, i know that the D100 rules in the battery department, but "ah gots to tell youse all that I'm getting 500 - 600 photos before I have to recharge or change batteries in the S2 Pro, and that really "ain't" that bad.
I guess what I'm saying is that after having the luxury of being able to consistently use both units on a daily basis, both have pluses and minuses.