I will raise this one from the dead again, just because people use google (i did).
There may be faster bottles, but i think these balance looks and speed. I use the plastic cages (i think they are fibreglass reinforced composite) and they are fine. No ejections ever, and i hit some rough stuff. I think there were design updates to resolve retention issues, and i no longer think you can get the carbon cage versions as of this writing.
And yeah, they are rattle traps when empty. Another negative is that bumps can cause water drops to fire out the spout. So if the bottle is overfilled, your bike can get some drips on it. As a result, i would never use them for sugar/electrolyte drinks.
I have thoughts about using one bta on my aerobars. They would be a great fit for a narrow arm position, and pretty aero. Downside would again be leaking on the bumps as water would always be at the spout.