If the presentation should have the double function of providing a manual later on, then you are correct. So you sacrifice a little clarity at the presentation for better value later. For the presentation alone a picture/diagram would still be better

About the pictures: Good point about the resynchronization. But I think the distraction is no danger for people already lost. It is a danger for tired listeners, for listeners where the coffee is wearing off, for everyone after the one hour mark into the presentation. On the other hand your point about keeping the ones with lost interest entertained is in these circumstances very seductive. Can't argue against that.