Just bought Fastpack 350. I know its very big but it suits with my needs when I want to travelling to other places for days and need to bring extra clothes and laptop. I had a thought to get Fastpack 250 or Kata 467 but I change my mind. Fastpack 250 is not big enough if I want to bring extra clothes. And Kata, I dont really like Kata's design. The zipper for the camera pocket is on the back which I dont like. Who knows someone trying to open the camera pocket when we're walking on the crowded.
Fastpack has better design, at least for me. The zipper for camera pocket is on the left side, so its easy to control and more secure.

If I just want to take pics around KL, usually I use my Tamrac shoulder bag (dont remember the series). It fits my 40D, 24-70, and 70-200. And doesnt look like a camera bag.