I understand that many, perhaps most of you moved from a heavy tobacco habit into vaping, & as such have made a significant, positive change to your health, but I think these symptoms should warrant real concern. This isn't empirical evidence, but after vaping for 1 day, & just a handful of times, I experienced a heavy, shallow senstation in my upper respiratory tract, & a big, fat ulcer on my tongue. Most of my vaping was with nicotine-free cartridges; I only briefly used a "high" cartridge. Doing this regularly could dry out my respiratory tract & alter the pH balance in my body, both of which are genuinely dangerous. Vaping may be the lesser of two evils, but these risks might be enough to dissuade me from the whole thing.
I don't like that these products come from China. China has a poor history of quality control & responsible, sound production. China's messed up, frankly. I see that some of you are making your own fluid, perhaps this is the way to go. Distilling your own flavors & adding them to domestically-produced vegetable glycerin sounds a lot more reasonable than getting a bottle of Chinese mystery fluid with 15 chemical components.