I found this on the old Blindwrite site, at http://www.blindwrite.com/faq.htm :
Safedisc 2 is a very hardware orientated CD copy protection. In addition to all the Safedisc 1 tricks, SD 2 uses a mathematical sequence of data which requires a very well contrasted CD to be read correctly. The explanation is far beyond the scope of this FAQ, the result is that only a few CD readers can read the backup of these mathematical sectors. Both a good reader and a good CD writer are required to produce a working backup, and a SAO RAW writing mode should be preferred, as SAO writing offers more contrast on the backup CD than DAO.
Is it true ?