Cleaning and the stiffness/inflexibility of the whole thing are going to take some getting used to! Not entirely convinced these will be taking off in a massive way any time soon...
Maybe they could have the last few inches made of a rubberized/plastic material which would slide over a lip (to ensure a seal for suction). This tip would allow flexibility and would also avoid painful accidental biting on metal.
Biting could be one of it least problems. Consider a scenario of a kid using this in a car going over a speedbump.