Maybe it's me...but though my 510 gets warm, maybe very warm, I wouldn't categorize it as hot. At least not so much that I get concerned about it. Perhaps I should. And I definitely don't carry two atomizers around. Maybe there's some difference from one to the next? Mine are manual switched...could that have an effect?
It all depends on your vaping procedure. Some vape harder than others. Get an extra long drag by holding the button down longer then the atty gets hotter. Some people don't vape hard and they don't heat the attys as much. It's all proportional to how long you hold the button down. But, that's why we love the manual batteries.
Kevin