Alright, heres the feedback:
I'm coming from eastmall 510HV atoms (4,2ohm new, 4,8ohm used), versus this atom with just 20 minutes of tests:
4ohm coil is about 2.5-3mm diameter, 1cm long, 0.18kanthal, 5.4V under load, ~7W
vape, 10mg/ml 40% VG 60% PG, cotton wick (not boiled, just cut and rolled).
Taste: Fairly similar, more clean, some sides of the flavour are more recognizable, others are muted, I can now "taste" the typical smell of pure nicotine
juice, if that makes sense, try to open your nicotine jar and smell that, thats whats coming trough, granted I use 4 drops of FA flavours in 7ml, and my nic
juice is 1 year old
Vapor: less~same vapor, probably also due to the air intake I drilled being on the large side, and I'm not sure its positioned well, right now its slightly under the coil, however since you can screw/unscrew the cone, screw/unscrew the center pin on the 510-ego, and screw/unscrew the 510 connector, bend upwards/downwards the coil (between or above pins), theres a lot of room for adjusting
Wicking: First time with cotton (cut, rolled, slided inside the coil, about 2cm long), first few vapes were stingy, noxious almost, probably the "fat" from my fingers was on the wick, not sure but after a few non-inhaled hit its now gone, wicking seems good, its pretty damn juice hungry, the wick didnt expand as much as I thought it would so its not "so tight it pushes hard on the coil", I should probably try and make a new one but going trough the noxious chore right now..
Throat hit: Oh boy, what a mess, throat hit is hit or miss, sometimes slightly less, or onpar or slightly better but rarely, than the 510HV.
I get headspins and dizziness with a few drags, I've got faint nausea too, my guess is that, well I don't know, no weird tastes or smell, probably too high nicotine for the new setup, not sure why the throat hit isnt reckless as a byproduct though. I should probably make some PG/VG only juice and see whats it like, back throat scratching is gone though.
Overall I'm not sure it was worth it

with the time and money you could very much just buy a premade rebuildable atom, if you already have tools (file, soldering iron), the few spare parts (510 connector, 510-ego, cone, 801 rubber tip, some IC pins, 2 sewing needles, kanthal wire, wick of choice), and enjoy building stuff then its alright, the cone hole with a file is going to take you a while, its
sturdy.
If you don't mind fiddling, changing the coil/wick is also very simple, needles on IC pins holds the coil remarkably well, you can turn the coil so that the holes to the spiral are exposed for easy wick treading with a needle.
I know walls of text suck, pictures when I get a chance with the few instructions needed to make it.