After returning home to Georgia, I tested my tarp in the pouring rain. I tested it in the desert environment of Zion, and found 5 workable, shade providing pitches for it.
has a series of short videos showing this.
This tarp shed rain very well, and even the center reinforced hole didn't leak as I expected. It felt wet, but no drops made their way through. I think a better application for this hole is a loop or tab for guy out points. Right now, I haven't decided to sew it shut, though, and will continue to experiment with using it.
More photos and specs are listed on my other blog
I plan to keep this tarp for other uses as well, namely a vapor barrier because of the Velcro sewn around the perimeter facilitates a bag construction.
I definitely enjoyed testing it, and making the videos. It lends itself to creativity. The more you can play with it, the more uses you will find. A fast packer or day hiker could have this as their sole/emergency shelter.