I think the fear is around the fact that there seems to be a very high influx of new vapors lately that show up on the board saying "hey, I've never vaped but I want to wrap this wicked quad-nano-dragon coil I saw Rip Tripper build so I can blow huge clouds". Frankly is scares the bajezus out of me too and I've tried to slow more than one person down for safety reasons.
Is it safe to stack batteries in the Vamo? Yes. Is it safe to stack in many mods? Yes. Are there general rules that need to be followed? Yes. The fact that the Vamo wouldn't fire the build wasn't "because" it wasn't loaded with stacked batteries but rather due to the fact that the build was below 1.3 ohms which is the safety threshold on the Vamo. Stacking the batteries tricked it out.
It's just a growing concern. No offense intended to the OP here at all. I think with many, myself included, is that when we see somone with only a handful of post who wants to "chuck big clouds" it sets off alarm bells. Has no one else noticed that as little as two or three months ago what was concidered a crazy low ohm coil set up was in the .5 range and now that is seen as just starting to get in to sub ohm? I know batteries are puting out much higher amps and are safer but am I the only one worried about people building .2ohm coils dual coils? Maybe it's just progression and we'll all laugh about it in a year but it does make me concerned that the "pros" show step by step how to build things like quad-nano/micro-dragon coils with no disclaimer about how the are very advanced builds, no reminders to be sure to understand battery safety, just "hoooooooooooohaaaaaaaaaaaaaaaaaaaa......she's chuckin' the vapor now"!
I love Rip Tripper, he is hands down the best coil builder out there and revolutionizes building every day. He has taught us how to rebuild stock PT heads and many others, he taught us chimney builds, micro, nano, etc. so this isn't a knock on Rip at all. Just think it may be time for a PSA reminder from all the pros as, with popularity of vaping on the rise, we don't want anyone getting hurt.
That's my $.02, ok maybe $.05 and again no offense to anyone! Just my rantings.