I just wanted to throw in a few first hand observations that might help someone who is debating between these two cameras. First you should go read the review on each at dpreview.com. I am only pointing out a few things. I own both and I'm about to sell the Rebel (300D) simply because the 10D gives you more control over metering and faster/more burst. The things I want to point out are just some deciding factors.
There are two things that I like about the 300D over the 10D. The first is the playback (review) of images. The 300 D displays your capture image a bit faster and at full quality. The 10D is a bit slower and displays the image at a lower quality and builds up to full, sort of like a progressive jpeg loading on a webpage. This really does not bother me either way because I disable review. The second is the write time of the image. The 300D seems to write to the card a bit faster.
I have heard some people comment about the quality of the 300D compared to the 10D. One was the CF Card Door being plastic on the 300D and seeming cheap. My comment on that is that the 10D also has a plastic type door in the same place as the 300D. This should not be a concern for anyone. One cosmetic difference here is that the 10D CF read/write light is right behind this door and they put a hole in the door for the light to shine through. The door does not really seal tight so the red light actually comes through the crack in the door. The hole points out to the side and is really useless but with the placement of the light they really had no choice. The 300D has the light in a different area and it is more visible. Overall the feel of the 10D is of course more of a quality feel but I dont see the 300D as being less durable. Lets face it, you drop either one something is likely to go wrong rather it be internal or external.
The 10D won me over with its burst capacity, more control and overall look/feel.
EDIT: I removed my last comment here pertaining to burst mode. Please read my next post below for more details on the burst mode of each camera.
Thanks for the info Widowmaker. Although the continuous mode on my G2 is slower than the 10D or 300D, I can often get a burst of 5 and sometimes as many as 7 (using high-quality JPG). A fixed upper limit of 4 in the 300D would be a real drag.
Yes thanks. You confirm my own thinking. I have decided to try and go for the D10. Do you shoot RAW much? What kind of frames/sec performance do you get in RAW? Is it much differant then the 300D?
bob