Answer
Start by separating what must stay stable from what can change in a bounded phase. Many IBM i ERP projects succeed when they modernize one module, one workflow, one reporting layer, or one integration boundary at a time instead of forcing a full platform leap all at once.
Buyers should ask every vendor and partner how phase one delivers a visible win while preserving operational continuity. If the roadmap only works as a big-bang project, the risk bar rises immediately.