Interesting. I would not dare to operate my S110 with more than 4.5V. If I use the S110 with a 5V power bank, then I always have a diode in series. But as it looks, there is still air up.
Cameras definitely have a gap. Official external power supply has a nominal voltage 4.2V but real measurement shows 4.3V-4.4V. It's really 5% error like all similar power supplies in this world. I'm pretty sure that camera design must have at least 1V spare gap so 5V must be practically safe to operate.
But still I cannot recommend to do that because of respect to Canon officials.
