What about the separate charger? Do you think it's necessary?
Yes, decent 18650 chargers are inexpensive. Why do you wish to charge batteries in the unit? You can of course but you really do not want to use the device & be charging at the same time, I don't think. Pass-thru charging under use is tough on batteries.
Regarding the HSA heater, can you sip on the TETRAx and take your time with the bowl, or is it really only for ripping through bowls in a few hits?
There are no rules, no restrictions with the Tetra, you alone decide how you wish to use it. The Tetra's flexibilty is due to it being a 510 flower vape, like the Splinter, Stempod, etc. I would prefer any 510 flower vape over the Mighty bc of this flexibility.
In your earlier discussion about the price points of the Mighty vs the Tetra, I suggest you might be overlooking the enormous advantage of mod use. The biggest weakness of the Mighty is its non-replaceable batteries. The Mighty batteries cannot be used in any other device.
Mods used with the TetraX can also be used with any other 510 flower vape, with concentrate attys, like the Sai TAF, Sequoia TAF, the DTv4, the upcoming AVS M22, as well as any 510 cart. I do not like bangers, nor e-nails, nor iso-butane devices, but that is strictly personal, ymmv, so my mods get a lot of use.
You do not require an expensive mod with say a DNA75c chip & e-scribe fw bc Lamart has personally optimised the Tubo firmware to work with the Tetra heater so that it is superior to any DNA mod. The Tubo evic fw is at least as good as Artic Fox, although AF does have auto-profiles.
If you wish to fly with a vaporizer, separating out the power source from the heater is a tremendous advantage. The Mighty must be carry on, but the Tetra could be in luggage, while only the batteries would be carry-on. In fact, one notable reason the Tinymight is so attractive a device is bc of its removable battery, unlike the Mighty, the Fury Edge, etc. Even in these earlier stages of development & even being overpriced, the Tinymight is much more attractive an option than the Mighty.
The Mighty impresses vape noobs bc of its "steampunk" like appearance, its reputation, & its ease of use. It is a very kool device, but otherwise, mine is rarely used, reserved for visitors or otg, by & large.