Quite a list you have of MYOG gear! Could you post some pics?
About the Epic - I had a similar experience with a Wild Things Epic pullover that quickly became saturated in a wind driven hail and rainstorm above treeline.
However, as I mentioned to you on another recent MYOG thread, I have been testing Epic (and silnylon) with 9" embroidery hoops weighted over bait buckets in rainstorms on my back deck. I was surprised to see that after a real nasty and lengthy storm, the Epic Malibu of the type formerly used by BD, both with and without Atsko treatment, had smaller wet out spots, less moistness on the inside, and no water in the bucket, compared to the silnylon, both samples of which had done very well on a Suter tester.
Maybe a greater problem with the silnylon is not just the amount of water resistance, or that it stretches while sewing, which can be overcome with practice and technique, but that it expands and contracts greatly on a shelter, leading to a lot of billowing (and therefore spattering), just the opposite of what one wants from a shelter. This makes it necessary to design a shelter that will cope with this, as both Warmlite and Roger have done very well; but it limits design choices a lot, and adds greatly to weight if you include a net or fabric inner. But with a good quality coating, the stretch makes it great for floors. Posted about this in Sept.
Hence the desire for light polyester fabrics for dome and single wall designs. The Pertex is nylon, according to the Point North, profabrics web site provided by Nancy, above; and I expect it would have the same stretch and sag issues as other nylons around 1 oz.(uncoated).
So, have not given up on Epic, yet. If I do, will opt for Cuben, knowing it will require a net inner (still lighter than Epic) and be a little noisy and a lot more expensive, especially if I have to buy enough to get the shaded stuff!