Basically the V1 and the Zest were a tad more air and the "Z" on the tank. Mine have been modified by GUS Mods to be more airy, but still a nice flavorful MTL, lightly restrictive experience. I liked the look of the V1 best, everything about it was great, at least I thought so.
Some people had filling problems, but it was a matter of not over filling and closing of the JFC and the air. It was basically a KFL that was prettier, better made and had more possibilities and juice control. So many love the KFL and keep looking for something else and this tank has been so overlooked.
I love it, and have the brushed and polished with 2 bases each for quick wick change outs.