[Long Haired Git]

Maybe we'll get a clarification.

I don't see any difference between a heatpipe and how AngryAlpaca thinks this works. The amount of SA at the condensor, and number of thermal interfaces at the condensor, are merely implementation compromises of commercial heatpipe waterblocks. The "home made" heatpipe (already linked within this thread) did away with the latter. Anyway, if the sole means of heat transfer is the evap/condense (bubbles), then its a heat pipe. Given two parallel paths, and returning of liquid via the same path, I can't see how any real coolant "flow" would be created, and the cooling of any flow would be immaterial compared to the cooling by the bubbles. So its a heat pipe.
Given this, then one large tube would be probably better, and yes AngryAlpaca's comments on the waterblock apply.

But I don't think its a heat pipe.

I think its a "syphon" as described. I think , as per a posting above, the bubbles contribute to fluid flow in that they go up one tube only, and hence there is a real "flow" eventually established. Not exactly a high flow rate, but flow none-the-less. This flow allows "normal watercooling" to contribute significantly to the overall efficiency of the rig.

However, UNDERBYTE's comments on condensor/evaporator design still apply, so I'll shut up now.