Limitations on running SSIS on x64, Both Design mode and Run Mode

Design Time:

1) Cannot debug Scripts

2) Cannot design packages in BI Development Studio on Itanium-based operating systems

3) If you want to select a specific 64-bit provider to configure a connection manager, you must have the 32-bit version of the provider installed

Run Time:

1) Cannot run packages that contain scripts—for example, in Script tasks or Script components—in 64-bit mode unless the scripts have been precompiled

2) May not be able to connect to as many data sources from a package executing in 64-bit mode as you can from a package executing in 32-bit mode

3) You cannot use the "Execute DTS 2000 Package task" in a package running in 64-bit mode as Data Transformation Services runtime is not available in a 64-bit version.