Stephen Roach, the chief economist at investment banking giant Morgan Stanley, has a public reputation for being bearish. But you should hear what he's saying in private. Roach met select groups of fund managers downtown last week, including a group at Fidelity. His prediction: America has no better than a 10 percent chance of avoiding economic ``armageddon.'' Press were not allowed into the meetings. But the Herald has obtained a copy of Roach's presentation. A stunned source who was at one meeting said, ``it struck me how extreme he was - much more, it seemed to me, than in public.''...