Any gotchas if we turn on GeoCoder after not using it for years?

Hello,

For years, we have been manually assigning our Geocodes to the employee's TARR & TARA fields and have been experiencing tax data 'challenges' . We want to turn on GeoCoder to automate the tax area assignment and would like to know if it presents too many problems to switch mid-stream? We understand the data might change (i.e. show the proper tax area) but wondered if anyone else has done this? any gotchas to be aware of?

I know we use BU constants and run BU batch, then EE batch jobs to update these two fields  ... anything else important that I would need to know to get this up and running?