Thanks everyone. Flash isn't really a concern for me; I work with natural lighting 99% of the time. The dependence on electronics kind of scares me... I don't intend to be using either camera in a monsoon, but it is bound to get a little wet from time to time. I'd definitely get a nice one, probably not used by a pro (EX+ on KEH is about $250 for the F3).
Having both would be really nice, but I doubt the cost would be justified. Once I'm able to afford the equipment I need to get, I would be packing either an F3 and an FM or a D700 and an F3/FM3a. In either case, I do like having a mechanical camera to fall back on. The only electronic manual focus SLR I've used was a Canon AE-1, with which I was thoroughly unimpressed. Perhaps my experience was just tainted?
Overall, I am inclined towards the F3, if for nothing other than cost (and my real lust for the 50/1.2, which the cost difference of the bodies would enable me to afford). But I just can't peel my heart away from mechanical cameras. Hence my dilemma.