Recently started playing with the T3 from SI. I have to say its the closest a bottom coil has ever come to not being a total POS for me (no offense Skelley

). The thing more or less just works. I have run into some wicking issues here and there (not often) but the good news is, the way the base on these units screws in/out for filling has the likely unintended side effect of allowing you to be able to control your juice flow (like the 100$ units that are the best bottom coils out there, Penelope, Odysseus etc). If you unscrew a tad, wick holes open up, juice flow increases and vice-a-versa.
People having issues with bottom coils makes sense, as they are incredibly sensitive to small changes. Wick hole, wick quantity, coil position, etc all need to be within a narrow range. If not, you get burnt hits or flooding. It cracks me up when people get a new pack of bottom coil "x" and freak out about how they're not up to par. NO bottom coil is up to par in so far as its not adjustable to some extent. So if you're not willing to adjust, don't buy!
If you're gonna make a bottom coil the only way to make everyone happy is to have an
adjustable system. Otherwise you will satisfy people using the 'just right' juice viscosity, vaping pace, and wattage.
Now I have to recoil this toy into a LR monster
EDIT: In reality all heating systems boil down to the same variables. I'm just saying with the BCs there is far less room for error. You can't just tip the PV and fix a problem with your wick slots, wick thickness, coil position, etc. Or (usually) adjust as you go.