Dual Write currently allow us to create new mapping for D365 entities that are not included in Dual Write Orchestration solution.
The issues that we have seen so far are how some of the forms in D365 affect the data sync between D365 FO and CDS.
For example:

Party Postal Addresses V2 (D365) to a Custom entity (CDS)
In the Vendor Form if you select a Vendor with an existing Address and edit (Quick Edit) any of the fields beside name or description (e.g. Street)
The Dual Write does not update the Custom entity in CDS.
However, for the same address if you instead click on Advanced and update the Address street there, the Dual Write syncs with the Custome entity in CDS

We see similar issues with other forms as well.

We have opened a Ticket as we think this is a defect but were asked to submit an idea here.
Ticket Reference: 2011060010002975

Thanks,
Rah