Is the Average Row Size value pulled in during RE of a DB2 or SQL Server database?

I'm not sure if this is a permissions issue, but I'm trying to use the Capacity Planning feature, which relies on Average Row Size information to calculate the storage requirements.  For Oracle, the Average Row Size looks fine, the Average width of each column is pulled based on the Oracle statistics, so it's very accurate.  But for DB2 and SQL Server, the Average Width of each column is the same as the Allocated Width, and no % Null information is pulled in.  So the Average Row Size is basically the sum of all of the max widths of each column, making the sizing calculation very inaccurate.

Has anyone successfully reverse engineered the Avg Column Width / % Null / Avg Row Size statistics for DB2 or SQL Server tables?

Is anyone using the Capacity Planning Feature in ER Studio for DB2 or SQL Server and if so, how accurate is it?