I have seen shots taken by Juza with a 60D and 24-105mm and it was good but not as good as a 17-55mm f/2.8 or 15-85mm, same holds true for the 17-40mm L except its even worst than the kit lens, check the ISO crops. If it's good enough for you thats great but there are sharper options out there if IQ is a deciding factor. FWIW unless you have a weather sealed body weather sealling is negated.

John.