I received mine from viper
vape today too. great service!!

ordered last thursday, shipped friday, received two davides today. I also can confirm the evod / protank heads work on these. I installed a protank coil on it straight away and filled it with some MBV butterscotch and am
vaping on it as I write this. like someone else posted, it performs pretty much identically to a protank. looks pretty on a provari though, I'm using it with a longer tip.
draw and flavor are pretty much on par with the protanks. I have two protanks and never had a problem with either. I'm a lazy vaper so I don't remove the flavor wicks or anything and I get no leaks on either protank even letting the
juice run almost completely empty on either one. I really like the convenience of these type of tanks, hopefully I'll get about the same on the davides. honestly, I am liking the puritank just a bit better out of the three. I'm not sure what the specs are, but the puritank looks like a slightly higher capacity, I like the way it looks a little better than the protank or the davides, but that's just personal preference. performs about the same, maybe a hair tighter draw but could be the tip or I've also noticed very slight variations in draw using different protank heads as they get replaced. quality control seemed to be a small issue on the puritank. it initially read lo ohms on my provari but I eventually noticed the center tube was a little crooked. I straightened it out with a screwdriver and it's worked like a champ since. the base on the davides fit perfectly on a provari as do the protanks. the base on the puritank is just a little bit bigger than the tapered end of the provari so doesn't look quite as finished but like I said, I really prefer the puritank just slightly over the protank or the davide. here's the puritank with the same tip for comparison.
I have a preorder for the protank 2 which should be out late this month / early next month but I'm pretty happy with what I have right now.