Yes, the poncho is similar to ThePacka unit, but the design of ours is actually my own. I guess it should be another MYOG article one day.
In addition to wearing them on Mt Jagungal here in Australia, we (my wife and I) wore these ponchos through France for 3 months, in some pretty bad weather. See http://www.backpackinglight.com/cgi-bin/backpackinglight/caffin_gear_list_revisited.html
'Bad weather' included lots of heavy rain and some snow.
However, I think the basic CedarTree Packa design is good, and very versatile. The sole deficiency is that you can't make a shelter out of it - but I much prefer a light tent anyhow.