Recently, I had tested Alexa XT in ProRes4444 1920x1080/60P compared to Sony F55 new firmware updated to record HDCAM SR Codec 1920x1080/25p at 440 Mbps to a new high speed SxS card.
The result was so interesting. The HDCAM SR Codec was so powerful enough for any purpose use.
I did not make any correction or any adjust to these clips. I just imported original footages from Alexa XT and Sony F55 directly into PremierePro CS6 and applied only Ultra Key, then saw the result.