The article linked by Little Hawk in the original post says,"When Martin began work on the 0-45JB, Baez sent them her original 0-45, as it was in need of some repair. While working on it, they discovered that someone had written on the soundboard in pencil "Too bad you are a communist!" Joan obviously found this amusing as the 0-45JB has the same inscription; but in reverse so that it can be read with an inspection mirror."

My wife had a D-18 when we were married, but, being just over 5 feet, she found it uncomfortable to play. About 25 years ago she got a 1921 O-18 and she loves it. It's an amazingly light guitar that plays and sounds wonderful. Her guitar is mahogany, not rosewood, like the O-45, but I'm sure the O-45 is great.
My only complaint about my wife's guitar is the bar frets. They make slides a bit difficult, but she doesn't do enough slides to make it a problem. I wonder if the O-45jb has bar frets.