What exactly is it about the F4 features that attracts you vs your F3? I've shot FE2 and FM2 bodies for a long time and last year got an F3 (no longer have the FE2). On a whim I got an F2 with a DP-1 a few months ago and love it so much more than the others I might just keep the F3 and F2. To me the F2 is the "Leica" of the Nikon bodies in terms of feel and overall quality of workmanship. The F4 and F3 seem fairly close in specs especially if only using with MF glass, maybe a solid all mechanical F2 might be a good second body? Just throwing it out there...
I'm open to that too, but I also quite like the sound of 1/8000 shutter and 1/250 flash sync speed. As well as having additional metering modes. They are handy.
Though I wouldn't complain if I came across an F2 with a meter less prism for a good price.
I prefer the F4 to the F3. I only use manual focus lenses, with the exception of a lone 50mm f/1.8D. I'm normally able to manually focus just fine with my preferred E screen, but if I get stumped, the electronic rangefinder works in surprisingly low light. The three LEDs of the electronic rangefinder bother some people; I like it fine. The backlit display of the F3 is a joke; the F4's is much better.
My F4 has the MB-20 grip; alkaline batteries don't seem to last long; lithiums are better. I find the hand grip very comfortable, but again, there are those that hate it. I'd say that the build quality of the F4 is inferior to the F3; it uses more plastic. Personally, this makes me less afraid to use it in the rain and dirt.
LTD_4224_001 by LJ Slater, on Flickr
I think it's settled then, when I'm ready I'll pick up an F4 with the MB-20 grip. So it's possible to get a K screen for the F3 and fit it into the F4? Will it affect any of the metering patterns?
No, it should not.
I personally wouldn't but it's more due to its size than its features. When I first saw one I found it hard to believe that it wasn't medium format and only produced postage stamp sized 35mm negatives.
I use Nikon N2020, N8008S, N90S and F90X cameras mostly with manual focus lenses. The focus confirmation with the standard screen or with an E (grid) screen are easier for me to use than any microprism, split image or combination screen. This is especially true for macro, telephoto or zoom shooting. Even the lowest spec model, the N2020, has many features and works nicely with the manual focus lenses. When you get up to the N90S/F90X there are certain modes which are not usable with manual focus lenses.
I've had the 1V before but they're still expensive I bought and sold mine for $700. I can get an F4 (or whichever body) for well under $200. Anything more expensive isn't on my radar.