Oh, and I have an evic and a vamo. (The vamo is brand new, so I'm using it exclusively for the next few days before I decide what I think.)
The vamo and evic are comparable devices - they both do VW, but they have different features otherwise (stacking in the vamo, for example.)
The provari isn't a comparable device. It just isn't, and all the fanboys who keep insisting otherwise aren't doing the provari justice. That isn't a knock on it, believe it or not. I actually think better of it in it's own class (VV) than against VW devices..
Some obvious reasons I say that:
It isn't in the same price range. (Don't compare a geo metro to a bugati, or an AMP tank to a prefilled Dekang cartomizer..)
It isn't the same type of device. (VW and VV are simply not the same. My mac and my nexus 10 are not interchangable. Ditto for my tv and my phone.. Sure, all 4 of those show video, but..)
There are lots of differences between the vamo and evic, too, but they are the same type of device. (One has higher power limits, one has more features, both do the same jobs within their limits. Land rover vs f350 maybe?)
Cost and fanboys aside

the one killer fail on the provari
for me is the single button interface. That is just me though, and maybe I am unnecessarily skittish. (I won an imotion, which is basically a cheap provari knockoff. It has a super sensitive button that also sticks, so it is especially irritating to click-clack-hold to change settings.. I realize the provari won't have that problem, obviously, but even without that it was annoying to morse-code my way to victory..)