By sensitivity to TH, I meant people who can't stand a certain level of TH. Interesting information though, as it point to the fact that not being sensitive to TH does not mean you won't have any issues with PG. Then again, TH is also dependent on your setup.
For me, the biggest problem seems to be dehydration; for many years before I started vaping, I've struggled with dehydration, probably because of PG in my albuterol inhaler -- I always wondered why even when I went off the albuterol pills, I still got god awful leg cramps -- now I know, it was the Pg, coupled with the fact that I've been plagued by hot flashes for about 15 yrs, and that causes a great deal of sweating! Now I add the vaping to all that, and it's rather unsurprising that my body is showing actual physical symptoms of dehydration. Pity. I've always been vain of my slender ankles. Now I seem to have developed cankles.

but I have substantially decreased my PG proportion in my ejuice, trying to drink a lot more water, and I take those time outs to elevate my feet. My mom says they need to be above the level of my heart to make the elevation really effective, but that's not easy when you have asthma, you're basically lying semi-upright but on your back, and that's quite problematic for me, it feels like there's an anvil on my chest.
Someone said something about sharp pain in the center of your chest -- I was having those for a while before I stopped smoking, but only when I was kinda stressed out in general, and/or overdoing the caffeine. I found it quite alarming -- my father had angina, and his father had multiple heart attacks -- but I'm glad to realize that I haven't had those since I left off the cigarettes! I hadn't even realized it till whoever it was said that about the sharp pains. I would definitely decrease the nic level! And the caffeine too, if that applies; I've heard round here that caffeine may have a greater effect on vapers.
Andria