Hi John, the epic double entendre comment was about the Houdini. It seems that Patagonia used a similar process as Nextec for their older, “Deluge” DWR which the 2012 and earlier Houdni’s apparently had (or so Richard Nisley has mentioned). Being a similar silicone encapsulation, it supposedly was much more durable, but also prone to contamination from dirt, oils, etc as EPIC is likewise (which is why both need to be periodically rinsed in cleanish water to refresh it, and occasionally washed with mild soap).
The Houdini material was a lot more breathable than a lot of the heavier, higher denier EPIC stuff, so silicone encapsulation treated fabrics can remain fairly breathable. A lot of it depends on how tightly woven the fabric is to begin with, and how thick the silicone coating applied.
Also, with lower denier fibers and woven fabrics, you potentially get more void spaces per area, so if not very tightly woven, it will tend to be more breathable than a similarly woven fabric with high denier fibers/threads. You can also get a higher HH per higher CFM with lower denier fabrics for similar reasons, and that the void spaces are potentially smaller, though there is more of them.