I just went through the "great debate" about the 24-105 f/4 vs 24-70 f/2.8. The negative reviews about the 24-105 from full-frame users at the Fred Miranda site pushed me to the 24-70 f/2.8. The big brown truck should arrive Wenesday, in fact. Now, I'll just have to worry about getting a good copy!! I also have the 70-200L f/2.8 (non-IS) so I.ve effectively covered 20-200 with two excellent lenses. Now, IS is very nice, but there isn't any substitue for f/2.8 vs f/4. I am (mostly) a tripod/monopod user so IS (while very nice) is less of a concern for me. I also own the 28-135 IS for my Rebel 350 which produces VERY good results in the 70-135 range. Since I plan to buy a full-frame body in ther future (perhaps there will be a full-frame replacement for the 20d) I can leave the 28-135 on it and use the L glass with the (someday) new body. Canon has solved some early problems with the 24-135 but I still am a little leary after comments from the full-frame users. Just my $.02.