People ask me whether I take care of the "messaging" of presentations as well. I do, but I do not really connect to the concept. Maybe it is because I come from the world of engineering and consulting, not advertising.
"Messaging" is often used in a marketing context for a consumer audience, not an investor audience. Should we emphasize that this gadget is beautiful, or powerful? In marketing presentation you would say "now in 3 gorgeous colors." In an investor presentation you would put a competitive analysis that show that the marketing strategy will focus on esthetics.
"Messaging" is often the basis for a design process that revolves around words and sentences. How should we call the benefit exactly. What slogans to use. I tend to think visual, and like to brainstorm concepts visually.
"Messaging" can sometimes come in the form of a prescribed flow of a presentation, we finished the messaging, now "just implement it". Not my kind of brief.
"Messaging" can also mean sorting out the company/product positioning. This is a big piece of work that usually falls outside the scope of a presentation design project. No story, no presentation.
So do I do messaging? It depends.