It is now possible to assign custom forms to specific membership levels. This means that you can have a contact details form for website members (business listings) and a different contact details form for general website users. 

The video contains the the instructions to successfully install the new Forms Update that lets you link a custom form to a specific membership level. 

The only current limitation to this update is that custom fields added to forms will not automatically appear on the profile page unless they are added to the listing details form.