according to a test by the evaporator world, I was initially not really convinced of the ViviTank. But according to the recommended in many forums Mod (air hole to the bottom and one at the top of the tank next to the steam part) I was super excited. So that part is roughly the BT V1 and now I actually evaporate the part only. Tastes great, draw resistance is now just as I had imagined and that a Super steam development.
Price / performance and to mod there are 5 star. Steamers are hobbyists, and I guess the small hole (max 1mm) and the toothpick to the air hole to make the bottom that can really everyone (no guarantee!).