Developing Storytelling with ESL Students

I am working with ESL students on developing oral language through storytelling. It's been a great experience. Students are very engaged in developing their stories and recording them on ipods. Something I noticed was that storytelling is greatly influenced by personality. Those students who are generally talkative took risks with their language and their stories showed improvement with each retelling. The stories had better word choice and ideas were better developed from one retelling to another. I also noticed that students who were capable readers had a better story sense than my struggling readers. Capable readers not only found the storytelling process easier but also struggled less with their story map and story writing. All the students were engaged in the audio recording tasks and using ipods or the computer, if working alone. There was some reluctance when sharing their story with an audience whether they were confident with independently working on their audio recording or not.  I have read many articles explaining the benefits of storytelling in developing literacy. I am having trouble finding research articles showing measurable data. Perhaps you know of one?

http://www.eric.ed.gov:80/ERICDocs/data/ericdocs2sql/content_storage_01/0000019b/80/17/8f/3b.pdf