At first sight, the only way I can describe those 2 lines of code is AMAZING!
A quick test on iPhone 6 Plus, where my (in development) game struggles heavily, with 0.4 resolution, has a dramatic impact, with almost unnoticeable fidelity loss.
I will keep on making some more tests though.
As for UI, to keep texts sharp, I'm thinking of the possibility of having the entire UI on the native stage, and having the game engine run on Starling with variable resolution.
Thank you very much Daniel for sharing this possibility.