The USB charger in the Tera is also very good, and quite fast (well as fast as you can charge one of these big cells I guess), but, I have cross checked the battery on my I4 and it charges to 4.2V for both cells. I see the Mighty is now out in a 2018 version... but still non-replaceable battery. and it only goes up to like 430F, which means you are gonna have a hard time with many waxes and concentrates. I need 4 18650s to get through a day without interruptions.
The large chamber on the Tera is also a win for me, I stick as much weed in there as I can and I normally have to start a second 5-minute session before the vapor runs out.
I filled my first jar of previously vaped weed this morning
The only things I would change on the Tera are getting rid of the plastic mouthpiece, it is a pain in the but to keep clean, and you really need strong lungs to suck on it. And the other thing is the intake on the bottom gets completely blocked unless you lift it up, which is an issue for some people with disabilities or mobility issues with their hands., That and I'd work on the intake to make the draw a bit easier.