So I filled up an EVOD yesterday morning & vaped on it all day. Although it's a bit soon to give any final score, it's worth saying that I already have no intention of ever using my Vivi Nova again as long as I have these around. The flavor & vapor production is insanely better. I am also at the bottom of my first tank & my juice is not a dark thick flavorless liquid as it becomes in the Vivi Nova. These bottom coil systems just feel like they were made just for those of us that prefer 100% VG. No it does not hold a lot of juice, but it holds enough for an average day.
I recommend watching
A PBusardo Review - The Kanger ProTank - YouTube to give you idea on how these are put together. Yes, this video is for the Protank, but the build, fill method & coil placement are the same. Not to mention, if you like these, you will probably want to grab some Protanks anyway, as I have.
I don't remember for sure if he mentions in this video, but it is a good idea to screw the bottom coil on as tight as you can with your fingers. Before I purchased these, I researched around & found that one of the biggest problem people have is leaking. In this research, I also found a lot of people who mentioned that they only had leaking before they realized they had to tighten them really well. I haven't had any leaking issues myself & I made sure to tighten this first fill very well.
You will hear some gurgling here & there, which IMO, is to be expected from a bottom coil design. With 100% VG VV juices though, I have not had any issues with flooding at all...I could see this being a potential issue with thin juices though. I will point out that even with the occasional gurgle, I have yet to have any juice come up the air chamber to the tip.
One thing about these that I am not terribly fond of however (which could be because of a poorly made adapter), is that they don't sit on top of the device perfectly straight. Despite my best efforts, I couldn't get it to screw on the top of my Provari 100% aligned with the device. Again, this my just be a poorly machined adapter. Don't let me scare you however, it isn't too bad & unless you are a crazy person like myself, you probably won't care. It's not enough to steer me away from using the device though.
**Addition: I think it would be a good idea if as many VV customers tested out these EVODS as well as the Protank. The more of us that prefer them with our VV juices, the better chance we might have of seeing them, as well as their replacement heads, available on the VV website.**