There are a few things that affected the picture when mtnbiker socal viewed them in his home. 1. none of them were calibrated and 2. the filter on the VT50 is darker which makes blacks appear deeper in bright rooms. If that's a problem for you as it is to mtnbiker socal, you might want to consider the VT50. Again, I never criticized him (or any VT50 owner) for their purchase decision, I just disputed the 75% claim where he basically feels that the ST50 is far from a VT50 in terms of performance. That's the only disagreement here. I understand why some would want the VT50 (features, styling, slightly better performance etc.)
Visual differences between sets can pretty much be seen through calibration reports/numbers/charts. Black levels and brightness are measured in foot lamberts or candelas per squared meter, and contrast ratio is calculated based on those measurements using certain test patterns. All 3 models have essentially the same black levels and are capable of the same brightness levels, so contrast ratios are more or less the same. The only time where the VT50 will appear to have better black levels is in a bright room because of the darker filter. As far as color/grayscale, DeltaE (UV for grayscale and 1994 for color) is used to measure the error % from reference. Under 3% is what is considered unnoticeable to the human eye. Again, all three models (ST/GT/VT) achieve this goal after calibration, but the VT50 has more extensive controls to make them even more perfect. But because the ST/GT are already fairly good after calibration, the difference between all three models is fairly small (especially the ST and GT where they perform the same). The numbers don't lie...
I don't want to name names to drag them into the argument, but clearly others in this discussion have seen both of them calibrated and seem to agree with me. Even some of the most respected calibrators in the industry (which again I won't name in respect to them) have said that they all perform similarly after they've been calibrated.
Believe who you want to believe, or wait for the experts to give their 0.02. Just wanted to make it clear that my claims aren't backed up by nothing and the basis of them are made through calibration reports / reviews. I'm no expert or pro calibrator, but as a DIY calibrator and a frequent visitor of these boards, I know enough to understand the numbers and can make an educated guess based on reports, discussion and reviews.