To me, a tank is just a bottle.
The DCT works fine on my end. No leaks, easy to fill, never cracks, and it's only my carry-around ego so it gets dropped/throw into pockets/left around alot.
It's cheap, does what it says it does, no issues.
Of course it uses a proprietary cartomizer which isn't absolutely terrible, but for the price it's fine. The liquid in the tank going down has only one place to go, which is into the cartomizer. If it isn't leaking, it's filling up the bottom of the cartomizer. You can only saturate so much of the filler by dripping from the top, so all it's doing is saturating the bottom.
I actually take a fresh cartomizer, fill it (30ish-40 drops-ish from the top), put it in the tank, fill the tank, give it a quick blow out to get rid of excess juice, then let it sit overnight. The next morning, I top off the tank, and I'm good to go for days.
I also use a Provari as my main PV, but it never gets the tank treatment, only atomizers and straight dripping.
If you're carrying it around, the DCT won't disappoint for the price paid.