> If you were designing the flight software for the Ariane 5, which choice would you make?

I would take note of the underlying hardware and what range of inputs are allowed and code appropriately. Stop pretending that your software doesn’t have a specific purpose and will run on an actual computer. If you’re doing finance you should be using fixed point integer arithmetic with two or three decimal places. If you’re doing physics simulations you need to be aware of how many significant digits exist. If you ignore your problem space and the kind of system your code is going to run on you’re living in spherical cow world and it doesn’t matter if you over- or under-flow because your software is garbage anyway.