Yeah, Ruth Eckerd sells to members first. They did the same thing with the SFTH shows. I didn't buy PBS tickets for those (I went to two of the three). I bought from Ruth Eckerd directly. For one of the shows I managed to score a Row B seat (which was basically like front row since there were no seats in front of me). It was a fabulous seat given how close the stage is. For the other one, however, I had a seat much further back (but I moved up to Row B during intermission, so whatever).
I think if you're buying a single ticket it's a little easier, but they do sell to members first. I expect these will probably sell pretty quickly since it's a Christmas show and there's only one.