I can see both sides of your dilemma. I was in a similar situation a while ago. I wanted an upgrade from my D50, and there was a cheap used old D1, but despite the image quality, I decided it would have worked out
worse than the D50, because it had less (or the same number of) focus points, 4mp compared to 6 (although what does that even mean anymore?).
So I held out and got the D300. I think that was a sensible buy. I mean, the only camera above it in the Nikon range is the D3, and I'm not a professional, so can't really justify the £2k extra.
Just thoughts