I also have a 2.6 16GB 256 SSD rMBP. It has a LG screen. It has at least two dead pixels. I cannot see them at normal viewing distance. I have no problems with image retention.
Most of the time, the computer is docked to identical home and office setups of two 30" monitors and a portrait 20", unreal connectivity for the laptop. When using the computer on the go, I cannot believe 1-how often I switch resolutions now that I can without it looking awful, and 2-how much I love the retina screen, even though I spend most of my time working in statistics programs and word processors.
I am perfectly happy with my computer, it is a great ~6lb (computer, power supply, case) productivity package, and I am glad I upgraded.