I think it's hard to say without the ST50 actually being "out" yet in a retail outlet to see and compare. In 2011 initial reviews of the ST30 compared it very favorably with the VT25, and if I'm not mistaken it even matched/exceeded VT25 performance in many areas aside from black level. With the new driving scheme for 2012 panels, and interesting announcements like FFD 2500, increased gradation, and Bluetooth 3D glasses , it sounds like the ST50 may give the VT30 a run for its money.
ht Panasonic TC-P60ZT60, Monitor Audio: Silver RX6, RX Centre, Radius 90HD; Martinlogan Dynamo 700, Marantz SR5006, PS3, Oppo BDP-103D
2ch Marantz PM8004, Sony BDP-S1000ES, JVC T-X3 tuner, Monitor Audio Silver RX1, REL T3, Apple TV, Peachtree Audio DAC•iT
lr Panasonic 50ST60, Sony BDP-S5100