Thanks for the feedback thus far, everyone. Imagine my surprise when scrolling through the pictures of suggested setups to see a winter setup slightly nicer, probably warmer, and just as heavy as my living room! Makes me rethink some of that "type 2 fun" spent in much colder shelters, but getting back on topic...
I've been in a bothy bag once for wind protection on the very exposed south rim of St. Helens. It's a great wind break, and a viable option in a life-threatening situation, but I'd like something that doesn't have to be all or nothing enclosed protection. Plus, I'd need a vent to be comfortable regularly boiling water in one no matter what fuel I was using, and vents and windows start to add weight. They are crazy fast to deploy, and cheap, on the plus side.
What attracted me to the pocket tarp, in addition to the weight, is how easy they appear to pitch. However, I hike with two poles, so there's no weight penalty going with a two-pole shelter and this would probably add significant head room. I guess I balked at the flat tarp idea because of setup time, but really it's not that time consuming to pitch a diamond or an a-frame if the conditions don't dictate something specific. If I went with a flat tarp, however, I'd probably stretch my weight goal a few ounces because a little more tarp area (thinking 8x8) and a little more line means that this could more comfortably double as a planned primary shelter. I don't know, maybe the right choice is to stick with a proven system (flat, square tarp). The price difference compared to specialized tarps is small, and for about 3 more ounces I do get a lot of flexability over a pocket tarp. Which is nice, because what I want in an open lunch shelter and an enclosed emergency shelter is quite different and hard to achieve both using something that's more specialized for one or the other.
Anyone else using something other than a flat tarp for these types of activities?