I was going to invest in L glass this fall, but after seeing the 1600 ISO samples that my beloved 300D will NEVER be able to do
I'd be careful about this - the samples I've seen are shot in ideal circumstances using carefully selected subjects and lighting. Your mileage will vary. In practice, good low noise results require extreme care in exposure, and good 1600s are possible with both the D60 and 10D, and should also be with the 300D.
It is true that noise levels in general should be better due to improved processing, however, putting 8mp on a sensor the same size as the 300D will work against this to some extent. Even my beloved Mk2 can only produce its great high ISO results if I get the exposure spot on - any hint of underexposure, and the noise levels skyrocket.
If low light work is really what you're after, I think investing in something like the 70-200mm 2.8LIS would serve you much better.
What are the limiting factors on the 10D / D100 that are preventing you getting these shots?
While both these cameras seem pretty responsive, and the shutter delay is measured in milliseconds, I was surprised how much "quicker" my Mk2 felt in comparison to the 10D. The specs don't seem to be that big a difference, but in practice it is (I'm sure part of it is down to shutter release design and other ergonomic factors as well). A Mk2 will give you that extra precision to capture the exact
moment ... I think you can only appreciate the difference by trying it (or the 1D for that matter).
In more general terms, no doubt the 20D is a further improvement on the Canon system, and I'm really glad I got my Mk2 when I did as I would now find that purchase really hard to justify. But I have to say, like Chris, I'm glad I've made the big step and can sit back and ignore the upgrade wars for the next few years.
Incidentally, the guys at LCE Southampton tell me they've been surprised by the number of queries they've had regarding trade-ins of a 10D for a 20D - no doubt this was a factor in the trade in price Martin got quoted. I got a much better quote back in April when 10Ds were still in demand!
Colin K. Work, Pixstel