Posted: 07/11/2013 at 11:23
As I said above, starting from frozen, above the 80 minute mark it's unpleasant. Unfrozen, I'd say you're looking at nearer an hour, which is what they recommend in the blurb. Up to these points it's perfectly drinkable, and for the most part cool.
I tried it on hot days and it actually served the dual purpose of keeping me cool via my arm. It would serve people very well just from this perspective.
In terms of hot and sweatiness, I must admit I do fiddle with it a bit, mainly the strap that's furthest up the arm to recheck that it's secure. It's very comfortable.
My water bottle is this, so certainly not small...
Of the two I prefer the Fitsip for hour-plus runs. Beyond an hour and a half, I'd go with the bottle, and I'm now in the market for a fuel belt as well.