Just looked around: Gatorade says that they don't recommend reusing their bottles, specifically because they can't easily be sterilized (they can melt in dishwashers). Which might explain why the bottles with "sport" tops have effectively disappeared from the stores.

About parabens (the existence of which is new to me): "While generally considered safe, concerns exist about potential health and environmental effects, leading some to seek paraben-free products." All of us choose our own level of worry in every area of life. Parabens will not be something I'll be worrying much about. Especially since those Gatorade bottles are about the only plastic bottles I use.

And, by the way, I would guess that the safety standards maintained by a deep-pockets company such as Gatorade are likely higher than those of most bidon manufacturers. And after all, I've never had to add bleach to a Gatorade bottle to rid it of that plastic taste.

For general interest, here's an article titled Bottled Water: Myths vs. Facts.