I have a Garmin with a sapphire screen. I've worn it every day for over 5 years, working on cars, in the garden, snorkelling on coral reefs.
In short, I my watch has NOT had an easy life. I've made no attempt to protect it or taken it off for anything except charging. There is barely a mark on the screen. A sapphire screen will be a hard requirement for my next watch.
I wear mine while rock climbing. The watch has been put through a lot of beating against all kinds of rock. I've already chewed through 3 straps on this watch. The titanium case is lightly scratched, but the screen is absolutely pristine!
This is my second sapphire Garmin, and it's absolutely worth the premium.
https://www.theguardian.com/technology/2014/feb/10/sapphire-...