As far as I know, they didn't change anything about the chamber or the quartz cup, they just re-adjusted the temperature/software. So when we were getting decent results on the old model at 250F the new models will have the same result but it will read 350f even though the temperature is likely the same, the read out was just off by like 100f, at least that's how I understand it. Maybe they can program it to heat more conduction or more convection, I don;t know, I'm just throwing out ideas.
I think there is a lot at play here with the miVape, I know there is a good deal of conduction because you don't have to hit it to get cooked herb but there is also a lot of convection because you get better results with a super loose packed cup, unlike a conduction vape where it needs to be packed for best results. It may be different on the new versions but I'm sure if you set it high enough and pack the cup too tight, your gonna get dark bits but that could be a good test, pack the mivape tight and let it sit without hitting vs hitting it to and compare. That might tell you if your getting really hot convection air in the bottom of the cup or if your just getting really hot conduction in the bottom of the cup.......
One thing I question is the actual temperature. When I start my Crafty or Mighty, the temperature starts at whatever the unit is at, so if its 70 degrees out then it starts at 70 degrees and it may take longer or shorter depending on the temperature the unit starts out. Now with the miVape, it seems to always start on the same temp and it takes the same time to heat up, I thought, so I'm not sure if there is something actually regulating the temperature or if it just is programmed and maintains a temp that the factory set it to.
Also, the old unit would reach temp fairly quick but I usually would't get vapor until about another minute later so that could mean a couple of things; one it takes time for all the glass to reach the same temp as the heating coil so the glass airway is hot enough to produce hot air for convection and/or it takes a while for all the glass, including the herb cup, to reach the same temp as the coil to produce vapor via conduction, most likely a bit of both. Another test for the new miVape: let the unit heat up to temp like 350f for at least 1:30min to 2:00 minutes without the cup in place, then put the cup in and take draws immediately to see if your getting vapor from hot air instead of vapor from conduction of the cup being super hot....maybe
I could get good results on the old model at 250F with a cup that was filled just right, there must be some room in the cup like
Archaicrevival showed in his video or you will likely get dark bits regardless if its a new unit or the old one because I think the bottom of that cup gets hotter (some conduction i'm sure maybe more) along with the convection which is the hottest at the bottom of the cup so if you leave enough room then it allows the herb to circulate when you inhale and keep it from sitting on the bottom where it can get dark and uneven.
I wouldn't give up on the miVape, try some different things out: pack it tight and set it low or pack it really loose and set it higher etc....I really enjoyed the old miVape because I could get great flavor with the tiniest amount of herb without any dark bits but there was a fine line between amount of herb, temperature and inhalations.