Well, first off the blaring Canon logo... The Canon's velcro (at least on mine) has frayed a bit and the fuzzy dividers (as opposed to the nylon on the Tamrac and also on Lowepro, Pelican, and many others) attracts junk, namely dust.
If you're not sure about the idea of a backpack - well you've run into the reason why many people own multiple bags. I use a backpack for carrying large amounts of gear to a single place when the trek is long (i.e. hiking, walking). I use a belt system when I'm moving around and need to carry a fair amount, but need it at hand quickly. No searching and whatnot. I use a shoulder bag when I need to carry a fair amount of gear to-and fro, and for everything else. It all depends on the situation.
It seems like you're the casual shooter, and a shoulder bag would do fine, I imagine something like a Tenba messenger would hold what you've got listed with a fair amount of room to spare. But then again, we all have to wounder what situation we're heading into before choosing a bag.