I can write you one lol
I had a bottle of PEG400 and used it like regular pg.
I did not notice much difference and since it's more expensive than regular PG, I never bought it again.
It was not because I not liked it or liked it less and since my flavoring pretty sweet to start of with, I also did not really notice the lesser flavor.
The purity in the context of vaping is not relevant for me, you also throwing in flavors after all.
The lower toxity I don't care about either cause I'm not feeling poisenend when vaping regular PG.