I don't have the tube, only the can, but here's my thoughts on the can:
Stackage: during the hit, with a fairly unrestricted vape, I'll get Stackage 1/2-2/3 up the can.
Clearing, it jumps right up to the top of the can, and a tiny but up into ye mouthpiece.
Sometimes during a hit the water seems to compound its stacking and go all the way up the can, then without adjusting draw speed it settle back down to its normal level.
This is with water about 1-1.5cm above the disc.
Clearing: it clears pretty quick, being a small volume piece, it's unique in that it's my only piece where I dont pull harder to clear.
Drag: not much, but there's certainly some. I'd call möbius pieces zero drag, as it almost feels like they are pulling for you. Some other high end pieces I have I'd call no drag, where there isn't any noticeable drag in the hit, but it's just not as free flowing as a möbius. I'd call this low drag.
There's a certain element of restriction, but it is really minor, nothing I could complain about.
My weed star double showerhead bubbler has far more drag than the DG if that helps?
This is also easily the most efficient at diffusing of all my pieces, by that, I mean most Stackage for lowest volume of water.
It's also the most even diffusion of all my pieces.
There's just so many tiny little bubbles of awesomeness
)
farewell.
They ARE awesome though 
never be a rat . . .