The labyrinth of agencies that passes for America's bank-regulatory system is once again under the microscope, but for the first time in decades, it is under serious consideration for reorganization. Three former supervisors recently sounded off about what works-and doesn't-among the web of agencies, which include the Office of the Comptroller of the Currency, the Federal Deposit Insurance Corp., the Federal Reserve and the Office of Thrift Supervision. Supervision of the securities markets, regulated by the Securities and Exchange Commission and the Commodity Futures Trading Commission, is also ripe for revamping.