I saw this interesting article that describes an experiment to see how the rate of your speech affects how persuasive you are. See http://www.spring.org.uk/2010/11/are-fast-talkers-more-persuasive.php
Basically if you're talking to someone who disagrees with you, if you talk fast you're more persuasive. But if you talk to someone who broadly agrees, speaking more slowing is more persuasive.
I thought it interesting to share given that speed of speech is something that varies between the different DISC profiles.