Move Commonly-Repeated Fields into a new Table
Yes, move it.  The extra join overhead will be minimal (if the right indexes are in place!) and you will get a performance improvement for all the other queries which don't use addresses because you will get more rows per page in Customers and Offices.

Down the road, any master data management (MDM) or data clean-up will be easier with the values all in one place.

Sticky points to look out for are common definitions of column semantics (is Address4 the city, say, for absolutely every possible address?).  This could be important for reporting, for example, or summarising sales by region.  Uniqueness could be difficult to define for any natural keys you may choose to create on Addresses.