DataMasker is compatible with Salesforce Shield and you should find no performance degradation or product limitation. However, one of the considerations for Shield Orgs is that the ‘Filter Criteria’ field on the Masking Object can not include a Shield encrypted field.
Salesforce Shield Org with Person Account Enabled
Shield Orgs with Person Account enabled have Account and Contact somewhat intertwined. Encrypting some of the specific fields on Account encrypts the equivalent Contact fields and vice versa. A list of fields that follow this behavior are:
- Mailing Address
- Home Phone
- Other Phone