If you wear a helmet you're less likely to pull your hair out?
The Helmet uses top airflow, so is supposed to have a less chance of leaking. Generally, this is true as long as you don't carry it around upside down. The Toptank is a bottom air design, but has lots more choices of
coils to use than what are available for the Helmet. Lots of folks like the Toptank (some still prefer the original Subtank), whereas the Helmet is pretty new to the market so I don't think you'll find as much user experience for it versus the Toptank.