Here's a link to a review of the European Panasonic VT50 plasma TV.

I probably need to read this several times, but from the sound of it, the ST50 probably has just as good as, and brighter a picture than, the VT50. The brightness is capped on this model, and is the same as the 2011 VT30 model. Although in THX mode, the brightness is much higher and the calibration is close to professional. The motion sounds a bit smoother on the VT50, which would encourage me to choose that one over the ST50. So far, I see no reason to purchase the GT50 model, because the VT should be had for just a little over the GT50 price.

Decisions, decisions.