I've never cared for the tarp-and-bivy combination. I hike in wet, windy country and wanted more 360 degree protection. My first choice was a GoLite Hut 1 which was light and could be fully battened down in bad weather.
I wanted a lighter option and the SMD Gatewood Cape works well for me. It provides the same level of protection as the Hut1, but eliminates my 12oz rain parka, so the net weight reduction is more like 21oz (the Hut1 is 20oz).
The Gatewood makes a great day hiking emergency overnight option too, as do all the ponchos made for shelters. Add one of the Adventure Medical emegency bivy bags and you're ready for anything.