Wish I could be of more help. I don't own any of the tanks you do, so my experiences is obviously of no help. As far as ohm drifting, indeed if it's not solid to begin with then TC is going to suck. I bought the expensive original KayFun v5. The ohms jumped all over the place. It was just released and everyone else was have a great time with theirs. I took it apart, back together it seemed good for awhile, then it acted up again, so I thought let me make the 510 bottom pin even tighter, as perhaps it gets loose when putting tanks on and off. That solved the issue on that tank, and was confirmed by later users.
Another ohm drifting issue was on my Merlin tank, this was fairly easy to find, the post screw had become loose, so the Notch coil was showing different ohms.
Most of my other tanks are the ones using pre-made coils, and I bought any RBA's I could find, so when pre-builds go the way of the dinosaurs, thanks to the US FDA, I can still use them. Other then a few bad pre-made coils, I have not had any ohms issues, tanks like; Kanger Subtanks, Eleaf Melo, Eleaf LYCHE, Joyetech Cubis, etc. I own certain tanks that by their design are not suited for TC. Seems like you know your stuff, so if it's not the tanks, and you've ruled out the DNA mods, then it's truly a mystery to me.