Sawyer squeeze filter w/hose barb adaptor, 3L Camelbak,2 1L platypus plusbottles, gatoraide bottle
I usually always have the camelbak full while hiking and the others empty. The others are typically reserved for camp use or for use with the filter. Total kit weighs about 12 oz dry. I like the camelbak while actively moving for the sheer convienience of it, and the gatoraide bottle for camp. One platypus is used as the dirty water bag for my filter, and the other is just for extra capacity if needed.
I used to carry a MSR miniworks, 3 1L nalgene bottles, and sometimes a camelbak. That setup weighed 40 oz without the camelbak! So i was able to shave a good deal of weight, and i have not lost any functionality. The only change i make to this system is that in the Winter I will leave home the camelbak and add a 1L nalgene in its place.
With the hose barb adaptor i can very quickly setup in gravity filter mode, in line filter mode, or filter directly into my camelbak through the drink tube.