I caught this thread after the fact, but figured I’d throw in my 2c.
I spent 8 days on a tour with a Bivy, it worked so so. Was fine for the days where it was warm and nice, was an absolute nightmare for the couple days I hit rain.
-Changing is quite doable, not easy, but doable.
-Nice and light which is a plus.
-Super easy to set up/tear down, another plus.
-Not bad when it’s nice out and no bugs.
-Sucks to high heaven when it’s raining.
-No place to relax to get out of the weather.
-No place to put your gear if it’s raining. I had to toss my rain jacket over my stuff outside.
I’ll never use one again, I bought a BA UL1 tent which is much more comfortable and has enough head room to sit up. I also noticed that after a long day in the saddle it’s really nice to stretch out, touch your toes, side twists, etc. once in a while, all but impossible in a Bivy.