If you have solid content, you can give a speech with any structure you want and can switch structures quickly and easily. For example, Professional Speaker Patricia Fripp went to a conference where the speaker before her listed out his 7 talking points. Patricia took the structure of listing out the same 7 talking points, but instead used her content to demonstrate those 7 talking points.
Flexibly,
Tim Wilson
Professional Speech Coach
Free speaking tips at: http://speakingquicktips.blogspot.com