That fabric does breath very well and the water resistance in a way is a bit deceiving.
As a static hold it does keep that much water and probably more (I just put a liter because most can relate to that) and I know that it can take a good shower (I discovered that when I did the freestanding inner bit) however it will not take solid rain.
So in effect it works very well as a drip barrier but still breathes .
The reason I did that inner freestanding bit was simply because the usual critics came out with that objection (you know the : great tent but...you cannot have the inner up by itself") not that many do that but was just to show it can be done.
(I made my own pockets to sit the poles in, the pocket connect to the four corners)
In reality if you leave both doors open there is plenty of exposed areas with the fly still on.
Franco