Hey RJ - Its nearly always 100% VG for me. PG gives me the "heavy lungs/tight chest" problem.
Thinning: I guess it depends on your delivery device but honestly I've not had any problems with my clearomizers (CE3's Kanger T2s and 510 Excaliburs). Not even a little bit. I suspect that most vendors do the thinning for you to make it deliverable in your device. Either that or it really does have a severe impact on some devices that I'm personally not familiar with.
On the plus side for flavor selections - By choosing 100% VG wherever I can - ie with Heathers - and changing flavors during the day, I have found I can tolerate PG in other flavors when that's the only way they come.
As to weaker flavor, it's tough to answer that one as I've not ordered the same juice at 2 different VG/PG ratios, and other times I order extra flavor because I have the 100% VG option. Maybe I'll get a sampler size and see if the flavor changes on a couple. On the other hand perhaps that's why with Heather's I personally taste strong and different flavor notes with succesive puffs - the chocolate, the caramel, the vanilla and mocha coffee flavors instead of "tobacco" - would I call it or many other RY4s "tobacco"? No. Does that matter when vaping Gandalf. Heck no! It's wonderful stuff with individual strong flavor notes instead of a mud. I've compared Gandalf to being provided a fresh ice cream sundae when many other flavors consist of the melted muddy remains in the bottom of the bowl after someone's eaten it.
However, I should add the proviso that "tobacco" in my dictionary is more along the lines of a cigar, or other extracted tobacco like Devil Dog, though in DD's case I don't like that one specifically because of the latakia.
Hope that's of some help. Keep us updated! PS the superior intelligence durakitty told me to say Hello and her wish is my command.
After thinking on this a little while, and realizing I've probably had PG allergy/sensitivity reactions to some other things over the past few years, I'm going 100% VG. I was wondering if the 100% VG folks try to thin their juices? HHV is getting an order from me today at 100% VG. I'll need to vape for a couple of weeks to pinpoint any improvement. And I think I'll go get allergy tested as well. I thought my brother was the only one with allergies?!? Who knew? After googling, it seems PG allergies are fairly common. The list of other names for PG is HUGE too. It's in everything. So no Swisher Sweet juice for me as it isn't in her Purity line. I'm also glad my Highbrow can be requested at 100% VG with extra flavoring. I'm now 100% VG all the way. I'm glad I can vape most anything because now I can't purchase samplers for testing with any PG. I'll just have to order wisely, and really look at reviews of juices, to see if it's something I'll like. From now on, the only moisturizer going on my body will be unrefined unbleached organic coconut oil. LOVE THAT STUFF. Thank you HHV for offering a purity line. WHEW!