What are the Pros & Cons of sticking to default Story Size vs. going larger?

Not a contradiction Phil, I think I just read or understood Indunil's question differently in terms of how the story size is used just to set the slide overall size and the player sits around that adding to the overall size based on what you've chosen to include in the player. Always good to have more than one idea or opinion shared! 

If you'll be using mobile devices, you may also want to take a look at this article which helps give you a sense of the different elements you can add and how they'll impact the player size and appearance.