My experiences:
Camelbak bottles - don't bother
Specialized bottles - pretty tight fit
Trek bottles - perfect
xlab bottle - interesting design, no leakage so far
I've also found its much easier to pull the bottle out with a twisting motion as opposed to straight out.
It seems that zipp extensions are a tiny bit wider than others that were tested, the mount doesn't exactly snap cripsly into place.
Camelbak bottles - don't bother
Specialized bottles - pretty tight fit
Trek bottles - perfect
xlab bottle - interesting design, no leakage so far
I've also found its much easier to pull the bottle out with a twisting motion as opposed to straight out.
It seems that zipp extensions are a tiny bit wider than others that were tested, the mount doesn't exactly snap cripsly into place.