I could have gone for the 40D if I had waited, it wasnt around at the time I got my 5D, however I still think I have the best setup, for me of course, it might not suit everyone.
I am finding that the 24-105L is absolutely perfect, AF accuracy is by far the best I have ever experienced with this setup, (if a shot is oof, its my fault, not the lens), its capable of very wide angle shots for landscapes & has a pretty darn good reach too, on the 5D is by far the sharpest lens ive ever owned, it was on par with some primes I tried a while back, maybe ive got a good copy.
When I want to fit more of a landscape scene in the shot, I will zoom to 50mm & build up the scene with several shots, the end result is something as wide as I want, with no distortion & a final image of 80mp or more, no im not talking about panoramic here.
Lets say I had stayed with 1.6x bodies, the 24-105L wouldnt be very wide, so I would then either have to get the 17-55IS which I feel would be a downgrade especially in build quality & very limited focal range, or I could have purchased a 10-22 to go with the 24-105L, but the endless swapping lenses would have become very tiresome.
I guess everyone views this in their own way, I see that a 40D is a nice update on what was looking like a tired 30D but thats about all, even if it does compete with the 5D's noise its still a cropped body, which you either want or not, it definately does NOT compete with the 5D, if the 40D was fullframe it might have been a different story, its very strange how its suddenly being compared to the 5D though, when noise levels are pretty much the same as the 400D, I never heard anyone say that the 400D can compete with a 5D before.
Its like saying a 40D can compete with the 1DMarkIII, they are both 10mp cameras, noise levels may turn out to be equal, but its still an updated 30D, its not supposed to be direct competition, MarkIII owners have purchased that camera for a good reason, same goes for the 5D.