I swear by my camelbak on the mountain bike.

Thought I wouldn't care on the road bike. WRONG. I didn't care when I rode with it, but then I rode without it. Huge difference. I still wear it on the mountain bike (only reasonable way to keep the amounts of water, food, first aid, and bike tools I need on a mtn. ride with me) but not again on the roadie (unless it's a crazy long, unassisted, leisurely ride).

I have XS, sloping top tube frames. I've still managed to get two full sized bottles on them (side loading cages are my friend). I do have to switch the seattube bottle to the downtube cage to use it, but I haven't found that to be a big deal.

I can see how a bike any smaller than mine would relegate someone to smaller bottles, which could necessitate alternative means of hydration on longer rides. Not many bikes are smaller than mine though! The OP could, if she chose, go to side loaders and run full size (or very nearly) in both cages. I can see why she wouldn't want to though with the awesome matching job she's done.

Camelbaks work for some applications, but they aren't the end all and be all some try to make them out to be. Certainly they have their drawbacks.