Good post. I never thought about the idea of buying class B on margin.
Love Buffett. He's a great man because he's terribly modest, humble and simply understands that value is found when companies invest in their workers, maintain a products quality and uphold core shareholder rights. I forget which Wall Street investment house had security fraud problems a few years ago (Smith Barney? Morgan Stanley?), but Buffett was asked to lead the firm's board to clean up their act. His leadership alone reassured investors and Wall Street to put their trust back into the firm.
http://en.wikipedia.org/wiki/Warren_Buffett
Probably the only other company today that meets similar profit margins consistently are Altria (Phillip Morris), 3M (excellent long-term investment) and GE (although last few years have been weaker than normal).
Happy New Year to all.