I've owned the F100, F5, and now F6. I also have a D700 for low light and high shot count stuff.
My F6 with no grip weighs about the same as the D700 without grip. Heavy, but manageable and has a great quality feel to it.
- Built like a tank
- Bargain for a pro quality camera
- Can use different prisms if that is your thing
- Matrix meter is outstanding
- Focus points are difficult to see
- Custom functions are a little clumsy
- Full-time pro body form factor
- Cannot use Nikon CLS systems
- Mushy rear command button
- More focus points and highlighted in red
- Removable grip when needed for hiking, etc
- Can use EN-EL4a battery in the grip
- Nikon CLS compatible
- Matrix metering for Ai lenses and can be upgraded to take pre-Ai lenses
- Command selector on back is more responsive
- Setting custom functions is much easier than F5s
- Pricey, but worth the cost if you love film
- No interchangeable prisms (not an issue with me)
One other fact I love about the F6 is the ability to download exif data with the MV-1 (I think F100 and F5 have the same capability). With the F6, it is super easy and I simply convert to excel spreadsheet, print out and store with my negatives.
The F100 is also an excellent camera and great if you only occasionally shoot film or don't need the features of F5 or F6. The F5 is a beast and takes just photos just as good as my F6. The F6 is just a lot more user friendly and since I shoot my F6 much more than my D700, switching from the F5 to the F6 was an easy decision.
Nikon F6, 50mm f/1.4G, Fuji Provia 100F
Sample of exif data I printed out.