Just found this on the review of the 65VT50 - quite interesting and in complete stark opposite contrast to what Gel said earlier in the thread
The Panasonic TX-P65VT50′s best contrast performance is reserved for the [THX Cinema] mode. This mode achieves startlingly deep black levels which measure at an incredibly deep 0.005 cd/m2, combined with whites that reach around 90 cd/m2 (we say “around” because it depends on the average picture level of the content). The only flat-screen HDTVs to better these results are the last KURO plasma televisions produced before Pioneer exited the TV business (not surprisingly, most owners of those displays are unwilling to part with them). Our review of the Pioneer PDP-LX5090 back in 2008 found black levels of 0.003 cd/m2, making the Panasonic TX-P65VT50′s 0.005 cd/m2 a very close match (it will be impossible to see the difference of 0.002 cd/m2 without scrutinising both screens, side by side, in a pitch black room). It’s taken a while for Panasonic to (more or less) match the absolute black depth of Pioneer’s long-gone displays, but they’ve achieved it at the 65″ size – in one of the picture modes. The overall contrast performance is still not as high, though, because the KURO plasmas could produce searingly bright whites as well.
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In the [Professional] modes, which do unlock the full range of calibration options, contrast performance takes a hit. Black rises to 0.016 cd/m2, which is still excellent, but is no longer in KURO territory. More worryingly, peak light output is significantly dimmed, with a full 100% white window measuring just 65 cd/m2 after calibration (down from an already dim-ish 70 cd/m2 before