Depending on your pack's configuration...
I much prefer stashing my tent (or hammock in your case) to the outside of my pack. This saves precious pack space (and thus allowing for a smaller pack). Also, when setting up in the rain, you have access to your hammock without opening up your pack and exposing everything to the rain. And when striking camp, you can pack up and close up your backpack -- then put on your rain gear, take down your hammock, attach it to your backpack, and be on your way.