Ability to permission control PDP pages and certain custom fields.
Clients often want to allow certain fields to be edited by (for example) project managers but not all fields.
The ability to select certain PDP pages or fields and toggle which security groups can modify which fields and pages would be excellent.
Ben Howard commented
The easiest way to do this is by using SharePoint Audiences. https://support.office.com/en-us/article/Target-content-to-specific-audiences-33D84CB6-14ED-4E53-A426-74C38EA32293 . Simply create a SharePoint group(s) and then add your users to that group and then target that to the webpart hosting the PDPs
I have a work around by having two custom fields, one which is editable and the other as a formula.
I put the calculated field onto the PDP that is open for everyone to see. I have another PDP that I control access via a sharepoint group, this PDP has the editable version of the field.
Cumbersome, but it is effective way of locking down fields that you only want a certain group to edit, like Approved Budget is limited to our PMO group for example.