I would agree with this too though Grin. Biscuit used to get frustrated with his bottle, as he could never get enough out of it for what he wanted, so i quite frequently watched him 'scrabble' at it trying to get more out.
I also found the bearings were useless more often than not. i had 5 bottles, from different manufactuers and locations and they all broke. Could be because they were indoors, i dont know.
Also about the comfort, im sure you're right. I'd hate to have to keep cricking my neck to get water! Much rather lay down and drink out a bowl if my head was level with it, as a bunnies is
Im not saying its gospel, just in my experience adn what i've read here