I have seen an MDM used to clean/augment Eloqua data at form submit. A repost to the MDM or an API (REST) call has been used. When the new record comes in it is noted as 'To MDM', once the MDM process picks the record up it is noted in Eloqua as 'At MDM', when the data process is complete, the Eloqua record shows 'From MDM'
In this scenario, Program builder is used to hold the record from Lead flow until 'From MDM' is the status.
This process is assuming that the only changes to Eloqua data is via a form submit and not another integration from CRM, event management, etc.