If a 457 plan does not adopt the amendment to use 2001 Required Minimum Distribution regs, is the participant essentially stuck with the old regs?

Participants in 401(k) plans would still have the opportunity to roll over the difference between the amount under the old regs and the amount under the new regs. Since distributions from 457 plans cannot be rolled over until after 12/31/01, it appears that participants in 457 plans have no comparable opportunity to use the new regs (unless it's a first time RMD that can be paid after 12/31/01).

Is there any reason a 457 plan would not just adopt the amendment?

The only reason I could think of would be that it was paying out on a distribution schedule based on the old rules, and did not want to have to recalculate distributions it had already calculated once.