ST50 and GT50 are very similar. The GT50 adds some thx picture modes, one additional hdmi input, a faster processor for the smart tv crap, and a few other items. Details here: http://www.avsforum.com/t/1403635/official-panasonic-gt50-series-discussion-thread-no-street-price-talk#post_21865487 Bottom line you get essentially the same picture quality so unless you need one of the features the GT adds you might as well stick with the ST and save a few hundred bucks. Or get a bigger one with the savings