Using the Stored User Data feature is great BUT when filters are changed on a report and records that previously had stored user data are no longer part of the returned record set, the user data for those records is lost.  Consider the following scenario;

A NL 'Rows' report based on the customer table uses a filter for 'Balance > 1000'. A column on the report is used to store User Data for 'Next call date'. 

Initially records are returned for Customers 1,2,3,4 & 5 and dates entered for the next call date for each of them. 

A refresh of the report at a later time now returns records for customers 1,3,4 & 5 (customer 2 balance is now less then 1000).

The next call dates for these 4 customers is is shown.

A refresh of the report at a later time now returns records for customers 1,2,3,4 & 5. (customer 2 balance is now greater then 1000 again.)

The next call date for customer 2 is missing on the report. :(