I've travelled to third-world countries [1] with mine and I didn't insure it. I can't say I'd always do this, however. It depends on where you're going and what you're doing. In general, it's not wise to be flashy in a poor place but the stainless steel Sub isn't as obviously expensive as a gold watch and probably wouldn't catch a thief's eye like an iWatch, even though it is well over 10x as valuable.

[1] https://www.flickr.com/photos/defender90/4246326395/in/album...