Can I switch from a non Encumbrance environment to an Encumbrance environment and vice versa

With reference to note 1086669.1 ,it is mentioned that the decision to enable Encumbrance is a one time decision that must be made at the time of implementation because of the risk of enormous data corruption.

Does at the time of implementation , means at the time of defining the primary ledger in General ledger or at the time of implementing the Purchasing module?

If we are only already using GL, AP, AR, FA and PO has not yet been implemented,  does it still have risk of corruption if we enable budgetary control and change the SLA to encumbrance accounting?