Okay, I was gonna stay out of it, but I'll go ahead and give Big Agnes a pitch. This isn't a problem with a BA bag due to the pad sleeve -- the attached pad keeps the bag positioned so getting in-and-out is easy enough.

I'd hate to try to get in and out of a standard mummy bag in a hammock, though. Like trying to wind up in a sheet without getting wound up in a sheet. I wonder if anyone's ever been choked to death by their sleeping bag?