I currently use a Mini Trekker AW as my large backpack and have run into a situation or two when I need more room. I am considering purchasing a couple of the SlipLock cases instead of looking for a larger backpack. The two I am leaning towards is the "Bottle bag" for a water bottle and then maybe a "Pouch 30" for my flash which what I seem to tend to need to find quickly.
Anyone using any of the SlipLock cases along with their LowePro backpacks? If so what cases and why?

