I used this tripod for some 4 second exposures at AK one night and the images look sharp enough when sized to 20 x 30 on the screen. This was with a 10D and 24-85.
I do not yet have any 20 x 30 prints from images where I used the tripod, I have some 12 x 18s and they look great.
Hanging your camera bag from the tripod should help, the review mentions pulling down on the center post for greater stability. It is surprisingly stable for the size and weight. I was a bit skeptical but after reading three good reviews I decided to try it and was not disappointed.
boB