Jen, see Nathan's post right after yours. I saw the original posts, and that is what i was primarily addressing.
I have previously ordered from Lawson and thought the service was acceptable and the products excellent and well priced.
But what does that have to do with the price of beans now?
Here is what it boils down to besides the interpersonal drama, and most people with actual experience with this form of Tyvek will tell you similar. If you are willing to buy a 1443R Tvyek Tarp for a 100 dollars, you are essentially buying a water resistant, throw away tarp that will have dramatically less mileage than a similarly priced silnylon tarp. It has very little tensile strength in comparison to silnylon. Tyvek homewrap is decent and comes closer to being water proof, is more durable and stronger, but it weighs more than silnylon and packs bulky–homewrap was one of the first materials i myog'd with.
Personally, if i lived in super dry climate wherein rain is rare, but Sun is hot and intense, i *might* by such a 1443R tyvek tarp for Sun protection for car or lazy man camping provided it cost less than 50 dollars–actually, considering the lack of longevity of such a material, i probably wouldn't pay more than 35 for same.
That's just me. And i don't know what Lawson is smoking when he repeats that this form of Tyvek is waterproof. It's not, not even close. Take a look at Dupont's site and the list comparing the different tyveks. Some of them are listed as having hydrostatic head ratings, but some including 1443R is listed as n/a. But do note the high porosity on that list–actually the highest on same at 69. If you take than info in combo, it begs the question of, so again, wth is he talking about as far as waterproofness?
http://www2.dupont.com/Tyvek/en_US/products/tyvek_styles/tyvek_styles.html