I'm also a "late adopter" and a negotiator to boot, so I always wait until the circumstances are best for making a big purchase. I like to buy a product that has been tested in the real world and has had its issues addressed or resolved. I'm also more educated about the product I want to buy and will ideally get it in its best version if I buy it late in its model cycle.
This holds true for the VT30 model line right now. I originally purchased the Samsung 64PND8000 from BB on 1/30. Between the new models on the horizon and the Super Bowl sales they had going on, I was able to negotiate them down to their cost.
When I ran into the buzzing issue with two 64PND8000 panels in a row, I decided to cut bait and the sales manager that I was working with at BB offered me the 65VT30 at their cost, which turned out to be $200 over what I spent on the Samsung.
I just received the Panasonic yesterday and I am thrilled with it's performance so far. Great picture out of the box on THX setting, no buzz, just a barely audible electronic hum at around 1-2 feet.
With this set (and the Samsung for that matter) I figure I have a product that has been through the consumer ringer and most of the bugs have been worked out. I think the buzzing panel issue with the Samsungs was just bad luck, but it seemed that the VT30 line was more stable.
Both the Samsung and Panasonic panels have had their issues over the course of the year - buzzing, brightness pops, peeling for the Samsung, color accuracy, green/yellow blobs for the Panasonic - but they both have been addressed by the companies.
I think that you will run through the same growing pains type of cycle with the ST50s. I guess it boils down to if you want a product that is ideally issue-free at the end of its model year at a discount, or the newest tech in a product that may or may not be ready for primetime that is also priced accordingly.