From what I've read (there was a very informative thread on the BPL forum a couple of months ago), I gather it was mostly a quality problem with the manufacturer. I have developed an interest in the Squall Classic (which I should have bought in the first place instead of the SMD Lunar Solo). I noticed on the Mountain Laurel Designs website last week that they have a "new 2009 spinntex" which they claim is 30% more waterproof than the old for the same weight, and they're starting to make tarps of it. I fired off an email to Gossamer Gear and got an answer from Grant that yes, they have the new spinntex (they use the same supplier as MLD) and so far tests show it's really improved and they are really pleased with it. However, they are tweaking the design of "The One" and Henry Shires is tweaking the Squall Classic, so it will be a few months before either of these is available.

I gather that the fabric MLD and GG use is not the same fabric as used in sailing, but specially adapted for use in tents--quite a bit more waterproof, for one thing. I'm sorry that I can't provide more technical info--most of that is beyond me!

EDIT: Here's the BPL thread. Read the post by Ron Bell of MLD. Note that prices are going up!

EDIT #2--The info I received from Grant at GG is now on the GG website.