Hi All, I am looking to change to a tank unit and need advise. I am currently using a protank 3 mini with a Vision Spinner II battery. I've heard really good things about the Kanger Subtank Nano but need to know what battery to use. I love pen batteries but read that you can't use a tank on a pen battery (is this true?) or do I have to move to the "box" model of battery? I want to keep it relatively compact, I tend to chain smoke when I'm home so I don't want the pain of constantly having to drip onto a coil type unit.......and taste is way more important then the amount of smoke I spew into the air. I want to keep it simple because I loved my protank 3 mini and pen batteries but want to upgrade.