well, that is what they say. i have heard seven years, too. the problem is the plastic is rough and stuff sticks to it and bacteria can hide right on the surface much easier. i have to waterpic with h2o2 daily or mine start to stink. its just that bad.
yea, it can keep the drill busy. i think you can buy better, but you better have cash.
me, i just plan on beating the odds by being smarter than my teeth, the fillings and the dentist all put together.