There is always some disagreement about this subject. It seems that condensation always pops up as the main issue, with single walled shelters. Weight is always cited as the big down fall of double walled tents...carry *two* tents??? Most manufacturors have compromised with a waterproof layer and some sort of mesh inner on double walled shelters.
Modern shelters with fairly new silnylon will not leak when touched. However, after several years of using the same tent or tarp, they do. The silicone coating, not a simple spray on coating, will become damaged and still repel water till they are touched. Spraying them with some form of spray dry does NOT restore the origonal coating. It is more a matter of "How much use on the fabric?" The best way to repair a damaged tent, damage done by water pressure or other mechanical stress, is to repair the coating. Not add a hydropobic spray.
All fabric are some sort of mesh. Woven fibers of some sort, whatever the weave, is a mesh. This varies from corse "landing" nets with knoted intersections to ultra fine nylon cloth. So, I am a bit confused when Roger says a second skin is the definition of a double walled tent. This implies that that even a mesh inner would count. Yet he was saying it does not. Sorry, Roger, you usually have stuff better thought out, but in this case, I don't buy it. Perhaps you mean a second waterproof layer? No...I am a bit confused...
Anyway, cuben is a film. Plasitic sheets are films. These are very different animals from woven fibers since these are chemicaly linked. Some plastics do not do this. They pretty much only link in one direction making strands. Spectra or Kevlar for example. (I think...it's been a while...) Some curl tightly together but don't really bond sideways. Anyway, lots of synthetics out there.
Idealy, you would like a double walled structure that is a perfect insulator. It isn't happening anytime soon. Condensation will only occur where there is a temperatur/humidity difference. Eliminate the difference, no condensation. Weather we are talking a single walled shelter or a mesh lined double walled shelter (or any type of fabric) we get condensation in our tents. How we deal with it is different. Until we have the "perfect" material for tents, that can eliminate the temperature difference at the condensing surface, we live with it.
There are other things to consider.
How warm do you want to be? A double walled tent made of two layes of silnylon with only enough ventilation to breath, WILL keep you a lot warmer than one made with loose mosquito mesh.
How many no-see-ums do you have? Bugs are a big downfall of simple tarp shelters in spring and fall(at least here in the north east part of the US.)
How cold is the ground? Laying down on rock or ice is much different than laying down on forest duff. But this starts getting into your sleep system...
Clearly, there is no one tent that will do everything well, even using todays materials. I like my tarp. Late fall, early spring...its great. After the bugs come out, I add a simple mesh tent under it, a lot like a tarp tent. When it gets cold, I much prefer my tunnel tent...it's just warmer even if it IS heavy. My solution may not fit you. Your conditions are likely different from mine. But, don't be put off by a simple manufacturors mass production label of convenience or some member that is hiking in the Adirondacks. There are too many different conditions out in the wild to say one is better than the other. There are too many personal preferences to say this is the best solution, because, someone, somewhere will easily cite their preference and say yours was incorrect. Rather, learn to evaluate your own preferences and needs before making a purchase. Most real tent manufacturors make good tents. Cottage people make great tents for the conditions they know. Out of context, they are poor choices. If I was camping the tropics, my choice would NOT be the same as it is now. Nor would a single walled tarp tent work well in the Antarctic winter.