Because Research Point and Wealth Engine are dependent on addresses as data points, it would be best if all addresses were in one place. RP and WE don't go in to the Journal of a record to find former residences. Former residences are a key data point for identification and wealth determination. Having that data accessible would be necessary in order to get the most from the other Blackbaud products,
Why don't you just create a "Previous Address" Persona - that's what we do. When someone changes their address, you copy the primary persona toe the Previous Address persona and then update the primary persona.