MTL vapers blow clouds! LOL! I dont get that whole line of critique. You "dont get why grown people are so into blowing clouds", but you blow clouds!?!?!?!?!?! thats a weird line of weirdness.
Right now Im using a pico 75, like you! I have a 3.5ml single coil rta on it, a 0.7ohm ss coil and run it around 11watts or 380-400f with TC . It is pretty much the same dimensions as the set up you are using. I only use single coil size mods, they last just as long for me dl as they did mtl because I use them much less. I also only use the same amount of liquid as I did when I mtl the difference being that I use much a much lower nic mg.
Its just as cheap to maintain something like a Serpent elevate as a vapefly galaxies mtl, there is absolutely no difference.
I could use lower ohm coils and crank up the temp and use less nic and I do have rta's set up that way but more juice and I do have rta's set up that way but thats not really my thing.
Anyway, glad you found your preferred way to vape.