Hi Chris,
Good question! Is the 20D "better" than the D70? Yes, in my opinion, but is it $500 better, and in the areas that you care about? That's up to you to decide.
<snip by CeeDave>
James,
Yes, everything I've read indicates that the 20D *body* is pretty impressive compared to the d70 (except center point options and maybe i-TTL), even at the extra 1/2 kilobuck or so. If that were the end of the story I'd buy the D20 (and almost did!).
BUT, the 12-24 DX has generally been reviewed more kindly that the 10-22 EF-S, and the 10.5 DX has not yet been matched (sharp, moderate price, fast -- and a prime is always going to be sharper behind a dome, right?). So my decision isn't just on the body, it's on the available package ... and there, on my assessment, it seems Nikon may have an advantage -- again, for the cropped sensors where a 14/16 mm just ain't wide enough.
I really wonder -- as "d-films" continue to improve, will Nikon's devotion to developing great DX WA lenses pay off, as WHOLLY acceptable sensors on smaller, cheaper cameras have a great lens lineup on Nikon but less so (at least at WA, where I live) on Canon? For me, that's the $5000 question. Nikon seems committed to the DX; is Canon gonna do as much with EF-S?