It seems like this was written for the designer, not developer, so I would also like to add one more thing. If you're a designer and tasked on working with a developer to make an app happen (or vice versa really), then work side by side as much as you can with that person and have regular discussions. You'll both drive each other toward a better project than just piecewise doing things in a more waterfall-esque approach.
It just seems impossible to take something with texture at 1x, and then scale it up. I often pick subtle textures for 2x, and then just drop or re-zoom the texture in the 1x version. How many people really have non-retina devices these days?
Do you do this as a series of images in any order, or do you use some tool such as Invision, to build interactive prototypes?
This is a distance vs. area mistake, right? I thought that a point is used as a one-dimensional (distance) unit, and is generally one or two physical pixels.
