Just so you know, I saw one report of an istick 30W burnt/vented on a granite counter top during charging, using the manufacturers charger. But that's out of many many thousands. I really don't think any mod is immune from rare failures due to defects, etc. I am considering the istick Pico for my next mod, small, with batteries you can charge either in the mod or remove and charge in a good charger.
I have an iStick Pico. It is a Very Nice Mod.
It was my Out-n-About Mod until I got a Tesla Stealth 40w.