I have hesitated on the Camelbak, I sweat a lot and I'm not sure how that would go. Maybe some of the women with Camelbaks can pass on how the fit/comfort/sweat factor is.
When I was training for a 1/2 marathon last year... I ran with my Camelbak. I really loved it. I run up to 8 miles with it on (I had to stop training due to running pain, so I never made it further than that).
I would fill it up with ice and water... and off I went. It didn't make me extra hot and I always had cool water I could sip on easily when I needed to. I also had something to carry my car key in.
For me, I think this worked better than a fuel belt... and I would think that something bumping around my waist would get really annoying.
Additionally, when I have run with a bottle in my hand... the ice melts really quick and I get sick of holding it.
"Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather, to skid in broadside thoroughly used-up, totally worn out, and loudly proclaiming: WOW WHAT A RIDE!!!!"