I have never done Toastmasters but heard about it and looked into it about four years ago when I lived in New Jersey.
I was an actor in NYC for three years and had no problem doing auditions, getting on screen, getting on stage, etc. But then when it came to doing extemporaneous speeches off the cuff, I would get nervous, fumble for words, and fail miserably.
Although I have never signed up, I feel that everyone could benefit from it. Even if people are not in jobs/positions where they need to speak to large audiences, I feel it does wonders for self-esteem, confidence, speaking trajectory, and annunciation.
This has been on my list of things to do in life. Great question. :-)