Capitalization and Large Fonts Can Work Against You
Everyone has had the experience of feeling yelled at during a presentation: the text on the screen is overly large and/or all in caps. Usually the person(s) responsible for developing these presentations have a fear of white space. Don't be afraid of white space!
Reasonably sized (and still readable) text with white space around it and between the text strings is much easier for an audience to read than large text taking up the entire slide real estate.
Don't do this!
This is just not professional. If you have made every effort to make the content powerful and persuasive, you don't need to rely on font size to drive your message home.
Do this instead
This is a professional layout that uses white space as a design element. You've gone to the trouble of creating content that conveys just the right tone and message. Be sure that the "packaging" is professional as well.