For some years now I owned and used the Lowepro Slingshot 200 AW. Because this bag pushes too much on my shoulder and has no way to attach a drink bottle, I looked for another kind of bag or backpack to fit my 2 dslrr's with attached lenses, a drink bottle and additional gear.
The Lowepro Flipside 400 AW fits perfectly and ergonomically and is a dream to carry; The slip lock system makes it possible to attach additional bags and pouches to make sure you have all the gear you immediately need at hand, The developers had an enormous eye for detail, not seen in other bags.
Unfortunately; the drink bottle holder of the S&F system does not fit into the slip lock system used on the waist belt!! The strap of the bottle holder is too wide to attach to the slip lock system..