>> Hyvent is 1.8 oz/yd2, membrane has a special print matrix so it doesn't require lining, but I wonder how well that works
I made a rain anorak with Hyvent from Quest. 4.3oz for a generous men's small. Fabric has a really nice drape. Modified pattern to minimize seams. I didn't line it. In terms of performance, it feels very similar to Marmot's "Membrain Strata" fabric... somewhat breathable, effective against rain. Not as breathable as eVent, imo, closer to GTX.