The idea of such a multiple-use item is really attractive and is in line with one of the important principles of going light. I therefore considered seriously the idea of a poncho-tarp and decided no way. First of all, I would have nothing to keep me or my pack dry when I'm setting up the shelter. Second, there would be nothing to keep me dry when I'm out of the shelter to cook and eat (in bear country), feed my dog, fetch more water, "necessary errands," etc. Third, a poncho hanging down my front blocks the view of my feet--and there are times I really want to see where they are going. Fourth, I often hike in the high Cascades or Rockies where rain often is horizontal rather than vertical. Murphy's law would dictate that it would almost always be coming from the side. Fifth, there wouldn't be room under even the Gatewood Cape (larger than the others) for both me and my dog, and an extra tarp or poncho for the dog would defeat the purpose.

So I'm a little less ultralight and, IMHO, a lot more comfortable!

Your Mileage, of course, May Vary.