While there are numerous variables involved in producing a vaping experience that will satisfy people with diverse preferences, being able to vary the voltage can solve some of the most dramatic variances. The biggest problem i have had with mods able to produce voltages above 3.7 volts is the requirement to use multiple batteries. Even with protection circuits in conventional LIBs one has to remember the general lack of production quality of most of the batteries and recognize that there is still a chance for failure with possible nasty effects. Until now, mods able to produce HV required stacked batteries. The ProVari shipping in a few weeks from ProVape uses a buck/boot IC to produce higher voltage utilizing a single battery. It can also reduce the voltage below 3.7v to allow the use of LR attys at the sweet spot as well. Additionally it is also the only HV mod that i have seen that offers additional protections built into the circuitry including reverse polarity protection and overload cutoff. You can view their site for the list of features, safety and otherwise. The batteries being offered for use with it are LiMn IMR batteries (High-Drain batteries) which use a safer chemistry battery inherently and thus require no integrated battery IC to manage the battery. The chemistry also allows MUCH higher discharge rates than conventional LIBs. This allows them to support larger current demands with better consistency as well. While IMR batteries can certainly be used to increase the performance of other mods, it still requires stacking them to achieve higher voltages. I have a ProVari on preorder and will post a detailed review after evaluating it with several brands/ohm atomizers after i have used it for a while. If it is what it appears to be then it will be a game-changing device. The production quality of ProVape's first mod was heads and sholders above any mod i had owned up to that point so i expect the ProVari will be well made as well. My point is, while there probably won't be a "best VV mod" for everyone, the ProVari stands to raise the bar for VV mods if it lives up to the hype. The Beta testers have said it's the best they have seen....we'll see. My point is if you are seriously thinking about spending 100-200 bucks on a VV mod, I'de wait the 2-3 weeks and see if the ProVari meets/beats the expectations. The features and safety would make it worth the wait if it does.