I chose the standard one with the removeable middle section in red for my speedy b25 DE. I don't use the middle at all- when I remove it, only the soft side of the Velcro is left so no scratches. I don't carry water bottles, and felt having that takes up more valuable space, even if I could use for my sunglasses. I felt having a removable section would give me more space to lay my long wallets horizontally.
I chose the single layer because I prefer less structure, but I think I should have chosen the double layer because I find when I put my phone in the samorga pocket it at times caves in a little and maybe the double layer would have prevented that (this only happens with my iPhone 6plus, not with coin purse, key pouch etc...). Overall though I love it.