I'm in possession of the last prototype, and used it on my recent trip to Peru. Worked great, I enjoyed having it, since i really dislike rain-pants. Breathability was still a bit of a concern for me when moving at pace, but it was weird weather, moving in and out of rain constantly, where you'd be getting poured on, then in glaring sun a few minutes later. I'd probably be less of an issue if the Kilt were cone shaped, but that would increase the cost of production significantly while removing much of the versatility toward other uses.
The version I have uses 1.5oz cuben which obviously was a bit overkill, and snaps instead of velcro, so I can't comment on the closure, other than to say the snaps worked fine also.
It definitely kept the rain off, and as someone else mentioned, it can be used successfully as a beak/door for a tarp. Saved me from a soaking since I had a last minute shelter change-up, and ended up having to use my spinn hammock tarp, which isn't really cut for ground use. Storm came in and I had to pitch the tarp low at the feet, but was pretty exposed on the head end. I wasn't prepared to use the Kilt this way, and hadn't discussed it with anybody previously, but luckily the idea popped into my brain just in time.
Here's a picture the next day: