not used a lowpro or thinktank bag, but been happy with 2 kata bags we have. I use my 3n1 all the time, its a lower end one than yours without 2 extra pockets and laptop sleave, probably smaller too.
i got a cheap carabina drink holder, and the tripod thing, so drinks bottle can sit in that and not float about all over the place. i think it was 14quid off ebay, south korea.
I wear it classic backpacck style