If you and your ex have reached an agreement, there are major risks to leaving this agreement as informal.
A verbal or informal agreement can cause problems down the line. There can be misunderstandings, or one side can attempt to change what was agreed upon if personal circumstances change.
For example, your ex may lose their job 3 years after you’ve been separated. At the time of your separation, you agreed to walk your separate ways without any financial claim to one another. Because your ex has now lost their job, they come to you and ask for money or a financial settlement.
The most important advantage is protection from risks such as misunderstandings of attempts to change the agreement by one side. If an Order is breached, consequences can follow.