just4kix,
I believe the profesional calibrations (ISF and THX) are meant to optimise the picture settings so that the images produced are as much natural and provide the exact (at least closer to) details what a movie maker intended to. Also I believe we all purchased the Plasmas to see movies without loosing any of the original details. So I think you would not only get used to the post calibrated images, but also enjoy watching them more than before on your ST50. I may be wrong in assuming this on your behalf and correct me if so.
In other countries, people pay to get professional ISF calibrators and get the calibration done just to enjoy the movies on their HDTVs. So I some how believe we would also enjoy the images better than before. In my case, I am using some of the settings that you suggested before and I got used to it. For example, with the reduced contrast/brightness settings (for the first 200 hours), I got used to it and I still enjoy the beauty of the ST50 performance. At the same time, I some how get a feeling that with professional calibration, we will get used to the new settings and also enjoy much more than before. Again, some one might say that it is all about individual preference rather than a mere calibration. If that is the case, I myself would not push for professional calibration, but what if the other way ????
Even if we don't get a professional calibrator, would it be okay to simply copy the calibration settings from net even if that doesn't get us to the perfection ? At least will that not be better than the current settings that we use ?