Just checked, and thru-hiker is still selling their current silnylon in yellow and gray for $12.95 a running yard. It was tested by Lance Marshall, and the result was posted here a while back, in an update later in his thread about making your own HH tester:
The material had some water penetration at 3358mm HH, where Lance stopped the test.
I don't know if it went up to 3500mm, but the results were excellent IMO. There are also some comments on the thread by Richard about another test to 3500mm, but they do not state if the material was from Thru-Hiker. I'm not using the term, "Shield," silnylon; because anybody can stick a name on something - it's the tests and the reliability of the source that matter more to me.
I have a fair amount of older silnylon purchased 7-10 years ago that is much better than most of what is now available; but the Thru-Hiker stuff is the first I've run into that I could not squeeze water through with moderate pressure from my thumb and index finger. I'm very impressed with it, and appreciate that Paul Nanian has gone to the trouble to make it available for a reasonable price.
I might prefer the 1.26 oz .18 black-tinted cuben that Zpacks sells for a floor; but it is a close call. I also stretched the Thru-Hiker material in a 9" plastic embroidery loop, and observed the amount of sag when exposing it to lower temperatures. It loosened in the loop, but substantially less than any other silnylon I've tested that way. i think it would work great on any tent or tarp that is tensioned, like a Warmlite or one of Roger's tents, so that slack is taken up when the nylon expands a bit. Nylon is just a naturally flexible material, and does expand during temp drops. Thinner nylon tends to show this more. I think all the very thin materials, including sub once ounce thinner cuben, have their issues.
Hope all that is of some interest to you.