Here are IMO clearer instructions for making an asym 11'x7'4" tarp
a member here, Sgt Mac, hung with this size tarp in a hurricane and didn't get wet. Needs careful orientation, and angling the "wings" steeply towards the ground. No space to hang out in bad weather when camping seems to be the main complaint. If you are backpacking, the (much) lighter weight will be a major advantage compared with a hex tarp.
As you point out, not needing a center seam is a massive advantage for a first time DIY.
I suggest you look at the videos on the Hennessy site to see how this type of tarp should be hung. Additionally the youtube videos of Mcspporan http://www.youtube.com/watch?v=OwzZTeAE3yc
I have a Hennessy and use the asym for backpacking (weight) and the Hennessy hex for base camping (massive)
Thanks allot I appretiate the links and info! Thanks