Couple years back I did 5 days in a bivy. It rained every day, and was really not all that fun. I kept my gear under a tarp, but still... get wet getting in, get wet getting out, put on your rain gear and stand around...
We were socked in virtually the entire time, and I was losing my mind. Not that a tent would have been much better, but at least you could move around a bit. I like the bivy for emergency overnight, and maybe a 2 night max planned stay. Don't think I'll ever break my 5 day record.
