https://technet.microsoft.com/en-us/library/ms345142(v=sql.90).aspx has a nice chart showing which objects each type of "Process" applies to (see the "Process Options" section). If you just modified the dimension only, then "Process Update"...

I wonder if something like this might work:

WITH MEMBER [Product].[Default].IsLocationDiff as
IIF(DISTINCTCOUNT([Location].[Default]) > 1, True, False)
SELECT ...

So I'm kinda new to OLAP too, but... I think it depends how your Products dimension is designed. You shouldn't have product descriptions being members of a hierarchy, but stored...

Can you give more information on your model? What dimensions do you have? How many members in each? What hierarchies?
What type of report are you trying to build? What...