What you say goes against common sense and experience. Pausing randomly in the middle of a train of thought is not on the same level as a carefully considered pause. There was a real-life case study of the difference on the Language Log where the subject was a presidential debate between Bush and Kerry. Kerry spoke at a moderate rate and made careful use of pauses--he had longer pauses before beginning his answers to the moderator's question, and he had shorter, calculated pauses for rhetorical effect. By contrast, Bush launched directly into his answer before hardly taking a breath, spoke hastily, tripping over his own words, pausing frequently and inappropriately during sentences in ways that did not suggest composure but rather confusion and incompetence. Obviously that impression was not helped by his other deficiencies as an speaker, but it was a major flaw in its own right.