Haven't looked into it much but from what I've read on the FT discussions, those nice thick o rings make a nice tight seal which is strong and is what holds it together. But if you're very active, I'd imagine it's not the most suitable tank.
Haven't tried that yet, but I read that there's a microscopic slit down there and you can needle fill it but very slowly and only at a funky angle. Some people have been grinding that bottom ring to thin it down. So far I've been doing OK with the plastic tanks, so fingers crossed for now...
How about the bottom-filling-by-unscrewing-the-base trick (just don't tighten the chimney)? Have you tried that with the Quartz kit?
I tried grinding that ring down with a dremel,but didnt have much luck.Almost had it done and my pliers slipped and screwed up the threads haha.As for unscrewing the base,that's how i filled it when i tried the quartz kit on the v1.I never tried filling it when i stuck it on the v4,because like you,i haven't had any issues with the plastic tank,and i actually like the way it looks with the frosted m-tank.The juices i have that i know are crackers or i think may be,i just use those in my fogger.I seen that black orchid you mentioned a while back,those are sweet,now i gotta get one of those to go on my black clouper box mod i recently got haha.It just never ends haha.Haven't tried that yet, but I read that there's a microscopic slit down there and you can needle fill it but very slowly and only at a funky angle. Some people have been grinding that bottom ring to thin it down. So far I've been doing OK with the plastic tanks, so fingers crossed for now...
How about the bottom-filling-by-unscrewing-the-base trick (just don't tighten the chimney)? Have you tried that with the Quartz kit?
The ones at Focal don't have painted screws!
I'm really looking forward to the black V4. Then I can have a radioactive Orchid (green mtank), a Batman Orchid (yellow mtank), a Prince Orchid (purple mtank), ... 
Like b.m. said, you could try it, but your capacity would be like 1.5ml. Then you might as well just use a magma.
The ones at Focal don't have painted screws!
Is that one of the "V6" versions at FT? Been looking at that one...
Speaking of FT...the "Five Pawns" or "KF V4" replacement tanks are almost the perfect height (just a hair too high which can be grinded down to fit, or use a wide-bore DT) with the V4 chimney and top-fill cap.
The V4 chimney works well with regular m-tanks and all other replacement caps. For some reason, the connection on the top-fill cap is up a tad higher.
