I've tried meditation several times, although I have not stuck with it for long periods of time. But from time to time I find it quite helpful. When thinking about mindfulness, I'm wondering what you mean. Specifically, I think you're talking about two different skills when you mention "mindfulness required by speech" and "speech consciousness." When I've done mindfulness training for stuttering it's typically related to noticing my reactions to stuttering and not necessarily a controlled fluency (at least "speech consciousness" makes me think of controlled fluency ... maybe I'm not understanding you)