I bought the 50" S60 today from Sears for $668. It's an April 2013 build and has the latest firmware (didn't need an update when I checked via the built-in WiFi). I did an initial calibration in the Cinema pic mode with Mid panel brightness and an unprofiled C6 colorimeter (I have an i1Pro spectro which I will use next time to verify the C6's accuracy/profile the C6 with). Anyways, the set calibrated great and the primary/secondary colors were way more accurate than CNET reported in their review of the S60. The black levels did match CNET's sample at 0.004 fL and I targeted a 40 fL light output as well/2.2 gamma. Contrast ratio (on/off) is between 9,000:1 and 10,000:1, though it could higher if I calibrate to a higher light output (via raising the contrast control and/or panel brightness to high).
Panasonic TC-P50S60 Picture Settings Cinema 9-29-13.docx 19k .docx file
Thanks for the benchmarks here! But you should know at my local Costco the "Club" version S64 is $599. Cheaper and it won't be a mirror. It's up to you, but I'd take it back and grab the S64 for a lower amount of money. The price may very by location so FYI I live in San Diego, CA.