What i mean is, I don't think its worth going to the trouble of getting a 3DTV for the effect, but it's nice to play with once in a while. Also, active glasses (such as those on ST50 and up), flicker at 120Hz - 60 per eye. A disadvantage of passive is that you have to be sitting fairly central to the set to pick up the 3D effect, whereas active gives you a bit more room to move (not much mind!).
I'm pretty sure they don't record 3D in passive or active, it's the TV's (or cinemas) which decide whether its active or passive. You find most cinemas use passive because the glasses are inexpensive compared to active.
At the end of the day, it's kind of personal preference, and having been hinted some of the future TV's from Panasonic, I hope that future generations will improve on the effect, and that more content is available to view on them. It's getting to the point now where they struggle to make image quality better each year, so they develop new things to put in, Smart TV and 3D for example.