Western wrote an answer about Black Diamond Hooped Bivy Sack on September 17, 2010
I'm a minimalist.
While Hiking on the Appalachian Trail, this bag have gotten too hot during the summer even though I don't really use anything on myself and slept atop of the pad and sleeping bag. So the temperature is a big factor.
For warmer yet wet season, I'll recommend a tarp tent system with some netting to prevent bugs from biting you. If it's a dry season, just cowboy camping will do if the dew isn't that bad via West versus East (PCT & AT)
It's a great bivy sack if the condition requires it. I've hiked for 800 miles or more with it on the Appalachian. For not too warm weather, I like to use light/bottomless sleeping bag with half-pad left in the Bivy sack & roll it up then stuffing it in long sack bag to save some time for the set-up/packing.