Hello Andy,
Thank you for your post. Yes, its early days for me with the 40D but I love the quality it produces. In my film days (which only ended last December) I loved push processing film to 3200 ASA, I like the feel of fast film having been raised on Kodak Tri-X!. The 40D "pushes" to 3200 very convincingly indeed (with in camera noise reduction ON), my own impression is that the results at the speed are similar to my 400D at 800 ASA, but that is totally subjective, I've not compared the two cameras side by side.
Tonight I was testing some of my lenses, photographing bright stars at full aperture. I've got some good glass, but I tell you, NONE of them focus at infinity where the lens scale says they should. This explains my frustration all year with out of focus shots, it seems to me that focusing using a digital camera doesn't work if you use the scale, perhaps film was more forgiving?. Have you had a similar experience or is it just me (I should say that I like using lenses wide at f1.4 or f2, except when using my superb Tokina 12-24mm which only opens as far as f4)
Incidentally the 40D should be an amazing astro camera, tonight I was shooting through thin cloud, 10 seconds, 50mm @ f2 and 3200 ASA. I swear I managed to pick up the North American nebula, I can't wait to use this camera for real on some good clear nights (not always easy from cloudy England).
All I can say is that if the replacement to the Canon 5D full frame camera uses the same sensor (or better) and Live View technologies as the 40D, then I can say that I'm definitely going to get one as soon as possible.
The 40D has finally killed off film for me, and I never thought I'd say that.