I don't know of anything recent, but I know for a fact that my stutter has changed since elementary school. Around grade 4 or 5 it was a lot more initial syllable prolongations, more part- and whole-word repetitions, and pitch raises out the wazoo. My escape behaviors were pretty bad too. Now it's almost entirely blocks. The upside is that it's not nearly as noticeable, but people also don't realize that I'm trying to speak now.