Have you considered the fiduciary issues associated with a split? Will the administrative, recordkeeping, and investment costs borne by the plan's participants and beneficiaries increase because of the split? Who would pay the audit fees - the plan or the employer? You may be able to argue that the decision to split the plans is a settlor function, but the implementation of a settlor decision is not. I wouldn't do a split if it would disadvantage the plan's participants.