Mortgage bankers have signed on to government efforts to craft a best practices slate for the subprime mortgage market. But some other industry players are taking a wait-and-see approach to the initiative. "I would like to offer our support for this important initiative," said John Courson, chairman-elect of the Mortgage Bankers Association of America in a letter sent recently to the Treasury Department. The agency created waves when Assistant Secretary Sheila Bair revealed plans to