5D2 vs 3 not much better ? Have you got used to the beautiful LCD, the speed, the AF? I shot one CF card full with images from my newborn over a week, when popped into the Lexar the Sandisk was somehow not readable ! Imagine my loss feeling! But I had set it to simultaneous write to both cards and easily recovered all shots from the SD with a big thanks! One week of growth between 4-6 weeks of age is like a decade between 40 and 50! It never comes back.
The noise even the low ISO noise is cleaned easier, don't know about colours - they are all manageable nowadays. But I can see if my shot is OOF, I can set AutoIso and give the camera to my 10yr old son or any stranger on the greet and be IF on a no blurry shot... I could catch jumps of kids with 6fps or do slomo video. Let's not touch the video except for those halflit evening minutes at home when you see 20000 at the lower right and don't notice it on the screen...
If you want a Sony sensor buy the RX100: mine is coming next week