I'm not a big fan of the included atty on the dripbox. I've switched to using a velocity clone and closing down the airflow tight (the only rda I had with a bf pin ~ I like it way better than the included atty). I don't imagine I'll be messing with the dripbox much more, though I might set it up for roadtrips this summer. Plus, you can use whatever rda/coil combination you want, but I believe you should be building for 3.7 volts.
I really loved the TFV4 at first, I paired it with a rx200 and used that almost exclusively for two months (mostly stuck to the triple coil). The bulk, battery drain, and juice drain all had me looking for a new tank. I picked up the cleito not expecting much, maybe it would be good enough that I could use my single 18650 mods again, they'd been collecting dust. I was blown away with the airflow and flavour of the cleito. I've barely touched anything else since. The vape I get from the cleito is goldilocks for me.
I've been messing with the dripbox and the theorem this last week. The dripbox is more of a curiosity, I can't see it being my go to. As for the theorem, I'm really enjoying a 1.6 ohm spaced single coil at 7.3v and 33w, with just the back/side airflow open ~ I'll have to get some ss wire soon. The notch coil had a moment or two that seemed promising, but it gunked up hellah fast, I was rewicking within a few hours, just mucky and black, and it was hard to maintain good wicking. Once I get the coils and wicking for it wired, I'll probably stick on the metal covered sleeve. Until then I use the glass so I can check on the wick/coil ~ I had forgotten how much dry hits suck.