Primary considerations are centered around the presenter himself. He is the primary user of the slides, so whichever system he is most comfortable with will be

Primary considerations are centered around the presenter himself. He is the primary user of the slides, so whichever system he is most comfortable with will be the obvious choice. Asking that the presenter dedicate less time to preparation and more time to constructing some sort of elaborate LLVM/emscripten PDF presentation just for the benefit of secondary users who won't/can't use arrow keys is fairly unreasonable.