I feel the true restriction of stuttering (for myself at least)...is the fact I just can't fully express myself. I might avoid words or entire sentences if I feel I will stutter and that just leads to a very shallow level of communication sometimes. I think word substitution is actually a negative side effect of stuttering rather than a technique...and it can lead to awkward, improper sounding speech a lot of the time. If my stutter were to improve 50% than it would be a different story.