I think if you know enough about the risks to mitigate it have at it all you desire.
I just worry more about the newcomer charging up his smok mod with the trustfire batteries inside, via a USB charger and etc. etc.
I'm not really going to advocate in battery charging with lithium ion batteries period. I do however own two radiuses and it's recommended to charge them USB and honestly, they'd die faster if I swapped the batteries out. I do have magnetic chargers, I do have the appropriate power wall wart, and I don't charge them overnight and I check their temps every now and again.
To be quite frank, my favorite thing about external charging besides safety is the convenience. I have some internal battery mods and to me USB charging when not at home is just a pain, and I am NEVER gonna use passthrough. Ever. Passthrough vaping gives me the creeps.
I think you can pretty much do what you want once you've achieved "Mistress of the Dark Nicotinic Arts," except that was a title I just assigned myself, so make of it what you will. (I.e. I do what I want, like give myself titles. It may be wrong. But I do it.)
Don't vape passthrough with your Trust fire batteries and your 90 watt settings in your two battery version Smok alien though please. Just don't.
I also think that cellphones have nothing to do with vaping, pretty much entirely. I mean, yeah, they are both electrical things that you plug in that do things and have batteries.
If someone ever combines the two I will salute vaping for remaining viable against the FDA whilst slinking off into the night, never to darken society's door again, etc. etc.
Anna