OK. You asked for it!!!! /lol
NO Mod is perfect. ALL mods represent a compromise. I have a collection! /lol I am not a fan boy! I have had my xpv 40 about 10 days and have never owned a protovapor mod before.
Pluses
Well built
Built to order
They FIX them
They UPGRADE them
They appear to use them. See:
Technical: DNA-40D & temperature protection | Protovapor.com
They prefer to fly under the radar. NO free units to reviewers aka "shills"

Screen is on the side of the mod mid way so it's easy to see AND you will need it to fine tune
510 looks beefy and well designed. Juice leaks just sit around it and don't flow down the side of the mod
The extra cost stand makes it a nice and sturdy man cave mod
No rattles
No blems on the aluminum housing
Appears to be a "function" over "form" build since it has an industrial feel to it. Pretty is nice but if it don't work who cares
They have experience with Evolv boards since they sell a 30 and upgrade same to a 40. As opposed to suddenly appearing from God knows where and entering the market. Assume the DNA 50 and it's a safe bet they will upgrade your 40.
Huge selection of color options
Fire button which is often a fail point on mods given it's use. Looks very well constructed and beefy. I ignore the blurb about space.
The screen is NOT crooked and looks properly aligned
The mini USB port is properly aligned and sits where it is supposed to as opposed to off center aka funky alignment
Very reasonably priced. Think bang for the buck!
Minuses and not necessarily for me but could be for others
Square form factor
Not a box mod
Some folks don't like to wait roughly 10 days for a Mod in hand. They lust for near instant gratification.
Not pocket friendly compared to say a REO Mini or a Vapor Shark
Bat is user replaceable but needs a wiring harness soldered to the bat and the mod must be taken apart to install same. They were trying to avoid a saggy spring or "clips" that fail or get weaker. NOTE: they will install for free or you can send them your fav bat and they will due the dirty work. Order an extra bat with harness from them. Mine came with xpv5.
May not be as cool looking as my ProVari and may not last as long but that takes years to determine
Atty does not sit flush and their is a reason for that. Screws and function over form
Concern over the "rocker" weal thingy. ALL functions of the 40 are supported. It actually works great and I love it. Others might let this scare them away since it's an unusual implementation
These are MY views and others may have different views. They might even wish to pound me into the ground /lol but that is the nature of evaluating a mod. As a point of reference YOU should also read the threads on ECF about the Flask, Hana, and VS40 to arrive at an informed decision. If YOU see more pluses than minuses then go for it. I'm a happy camper.
EDITED for clarity