Gore-Tex/Todd Tex and eVent are a membrane that gets laminated to some fabric. The membrane is stretched Teflon , that is the gray bit. So the fabric used to laminate that and in some cases a protective under layer , will determine the "breathability" as well as abrasion resistance and weight.
Rab have three tents made with eVent (they call them bivvies) , they are waterproof and windproof but they don't work well in high humidity. Essentially there needs to be a different temperature inside the tent from the outside to expel the condensation.
So they work best when almost fully sealed up in cold weather...
eVent is reported to be more breathable than the other type.
Epic and Soft Tyvek are more breathable but less water resistant. About 800mm waterhead. Silnylon ( as used by Tarptent/SMD and the like) is about 1200mm and some have problems with that.
Franco