Now that Panasonic GH2 is my default "walkabout" camera I have been thinking of ebaying my 17-40L to fund an Olympus 9-18 M4/3 to add to 14-140 & 20mm. However, that does leave a significant gap betweem Zeiss 21 and 35 on the 5D2. Neither Canon 28mm options sound stellar and I think 24mm is more useful alongside 35mm anyway. Do you think 24/2.8 is optically up to 17-40 at 28mm (when I think it is pretty good)? If I don't get the 9-18 (will use wide end of LX3 for 24mm!), it seems more sensible to keep 17-40, as it gives me 18, 24 & 28mm focal lengths to complement 21&28mm Zeiss.