I did toastmasters twice. Maybe 2 - 3 years total. First time I couldn't bring myself to do a speech. Second time I think I did 4 or speeches and even served as an officer. It is a very supportive environment and it makes you become more comfortable in speaking situations. Definitely a confidence builder. The table topics section of the meetings are useful as well. It really helps with impromptu speaking. You're looking to communicate more effectively? I think it will help for sure. Will it help with the stuttering? That's hard to say. It will bring yourself outside your comfort zone which will help in regards to dealing with your stutter. You will gain more confidence in these situations. Will it lessen you stutter? Maybe, maybe not. I do highly recommend Toastmasters.