The September 2013 release has a targeted fix for the Schema Compare error when working with large display text or high DPI. This release will replace the August 2013 release and contains the same bug fixes with this one additional fix. We appreciate your patience while we worked to publish this update.
Get it here
SSDT for Visual Studio 2012: http://msdn.microsoft.com/en-us/jj650015
SSDT for Visual Studio 2010: http://msdn.microsoft.com/en-us/jj650014