I'm only capable of 3.7 and 6.0v. I've been using them since the 25th of last month, and I have to agree that the single most impressive thing about them is that they do not burn. You can chainvape the heck out of them and get them scorching hot with no burned taste. At 6v, they heat up extraordinarily quickly and deliver a lot of vapor. The flavor is excellent as well. The temperature of the vapor and the fact that these don't burn makes the experience very analog-like. At 3.7v, it takes a couple of pulls to get them hot, but they deliver at 3.7 too.
I only have 2 negatives I can mention with these cartos. I have one
juice that doesn't produce much vapor in them. It is a 100% PG DK-TAB. I get flavor but hardly any vapor, so I think maybe these are just too hot for 100% PG. - The other mentionable negative is that these pop and spit quite a bit when freshly filled. I've had to put the silicone ring back in and put my drip tip on top of it to minimize having extremely hot
juice occasionally hitting my tongue (with other cartos, I've just thrown away the ring and never had anything like that happen). - That problem more or less goes away after the first fill as the filler swells up a little.