Here's some thoughts on the Eviva-T after using it as an out-and-about workhorse for a few weeks.
1. Reliable and consistent. I have yet to experience a single gurgle, any hint of dry hit. It really just works. When the tank goes empty, you get plenty of warning that it is time to refill, the vape very gradually begins to degrade.
2. It is very pocket-friendly. I was somewhat paranoid due to the third-cousin relationship to the Kayfun design, but unlike the Kayfuns I tried a long time ago, not once did I have any mishaps. It remains bone dry, even when upside down in my pocket.
3. It is a great vape. Some juices work better than others. But this goes for every atty I own. Suicide Bunny and HHV are stellar. I still prefer the Diver for straight-out desserts and fruits. This applies to the Eviva-T, I have not yet purchased the "D" kit to try it out as a dripper. It also produces an astounding amount of vapor at regular resistances.
4. Building is pretty straightforward. I've tried a few setups, single and dual coil, and have settled - for now - on a very typical single microcoil 30g Kanthal at around 1.4 ohms. Like every other tank I've owned, it does not IMO lend itself to sub-ohming, but it was not intended for this. I will try out sub-ohm setups on the "D" when I get one, with the SS piece instead of a ceramic.
After a year of vaping, I've tried a lot of devices, and I am in the process of thinning my herd, both mods and attys. The Eviva fits perfectly with the Spheroid as an out-and-about atty. It looks perfect on a Hana Modz red mini, and lasts all day on that 1200mAh battery at regular resistances and 10-12 Watts, which is where most people will vape.