Apple will be the death of us all with their ultra hi-res stuff
It is a 'cover,' not a semiconductor mask
Typically, a 2x magnification (400x300 image) looks decent at full screen on ALL my devices .
The rule should be: No single rule
Do you NEED fine, line detail? Hi-Res (800x600, not Ultra-res)
Do minor jaggies hurt anything? Std-res