The 256 character limit is for an individual file or folder in NTFS, you can have structures with much longer character lengths. SureSync does not have any limits outside those of NTFS.
The maximum NTFS path length is 32,767. The maximum path of 32,767 characters is approximate, because the "\\?\" prefix may be expanded to a longer string by the system at run time, and this expansion applies to the total length.
Further details are available in Microsoft’s Naming files, paths and namespaces article.