It makes me mildly depressed to admit it, but CML is pretty much on the head of the nail there.

Having seen a direct comparison between his D70, and my 350D, my nagging suspicion that I should have opted for the former has been confirmed. Mr McL, I was amazed at the clarity of your Old Hartley pics
http://www.themodernantiquarian.com/post/42286
(I can guarantee CML's assertions about photoshoppery folks, I saw the images as they were taken, and they have all that colour and clarity of the one in the link above, straight out of the camera).

Your rockarty-Wolfness, as I'm assuming you're gonna be wanting some pretty low-light shots (I'm thinking Cairnholy for instance) for the RA, I'd go for the D70 if it comes down to a choice twixt it and the Canon, despite price differences.
In defence of the Canon DSLRs, the 350D is the bottom end of the bracket, and I am still using the kit lens, so that might be contributing to the lower quality. Praps a better EOS with a better lens would see a marked improvement.

It might be worth thinking about what kind of lens is best for the RA, and then deciding on availability/cost of the lenses?

It's a headtwister of a job, but it must be worth doing the thinking *before* purchasing, not after ;)