First of all, OP I think it is unfair to automatically associate cuben fiber material with getting hypothermia. I am sure there have been reports of silnylon failures.
I have personally experienced some pretty good storms using a cuben fiber Zpacks hexamid plus(0.51oz). I have also used the shelter during the seasonal California Santa Ana winds with gusts up to 40+ mph with no issues. I am using the older Zpacks model that has sewn sections, the newer version is all taped and bonded, and should be stronger.
Here’s a link to a video that I took earlier this month while on the JMT. Encountered lots of thunderstorms and some large hail. Hailstones grape to quarter in size pelted the shelter; the material and seams held up. Wish I could give you the lbs/sq inch of force that the hailstones hit at, but I can tell you that it hurt to get hit and could of potentially left us with some welts had we not been in the shelter. Could have really damaged a persons eye had they been hit directly in the eye. I had to re-stake the tent afterwards because the force of the hail hitting the shelter partially pulled up some stakes and shifted others. Half of the stakes had 2-10lb rocks on them in addition to being staked in the ground.
http://www.youtube.com/watch?v=LUgaFCvF2KM
In the video, the person who retreated into our shelter due to tarp failure had an MSR silnylon tarp. Was an error in pitch though, no rips or seam failures.
Was a little scary especially since I was concerned that the ultra thin cuben might fail and leave us exposed to the elements. It didn’t though. Pretty awesome. If being able to take that kind of a beating doesn’t deem a shelter as 3-season bombproof I don’t know what does.
Cuben is definitely more susceptible to abrasion than silnylon…that has been my experience in the field. This doesn’t matter for shelters though.
Also, one other thing I like about cuben > silnylon is how easy it is to dry after a wet night of rain or condensation. Just shake it out or lay in the sun for just a few minutes. The material itself absorbs little to no moisture unlike silnylon.