You might loose about 10% sensitivity with screen protector on. But yet 10% is worth of sacrificing for the sake of the screen and keep it functional for long term.

Depending on which screen protector you are getting, so far, ClearProtector and Zagg are pretty good. If you going to get the cheapies chinese made one then there wont be any guarantee. Both companies described above guaranteed that they will refund or replace if anything goes wrong with their product. Both company claimed to be used by the military helicopter and some other protection. Zagg is incredibly strong and tough. So I presumed that ClearProtector is living up to its name as well.