I have the breathable, and LOVE it! But, I sweat a lot, and wear mine when it's hot because I get wet a lot (cat-boat - no floor). I also have friends who have the non-breathable, and love theirs too. OS has told me that the breathable fabric is harder to seal (picture the texture of goretex on the inside) and is slightly more prone to seam failure because of all that texture. They stand behind it none-the-less. I had a foot leak, and sent it back and they fixed it no-problem. They had already come up with a new system for doing feet and sealing seams. These are the fabric feet, which are really hard to seal too. But I don't want latex, so I'm willing to accept that.
I think if I was doing winter boating, I'd want non-breathable, so it NEVER leaked. Since I'm doing spring/summer/fall boating, and I sweat a lot, I want it to breath.
I know lots of Kokatats that leak awfully darn fast.
I have the zipper across the back, it leaks less, because the zippers are an easy leak and it's got less exposure to water than across my chest.
I love the made in the USA factor, and custom fitting.
Living in Montana, boating in Idaho