Due to numerous benefits of DFSR over FRS, its time to move to DFSR, considering the acurate steps are followed else things can become awry to your environment.
The issue with FRS was like Journal wrap error, blotting, inconsistent change notification etc, where as these issues has been fixed & greatly improved into DFSR. You can find more justification and benefits moving from FRS to DFSR in the below link.
The Case for Migrating SYSVOL to DFSR
DFSR can only be implemented when DFL is at 2008, FFL can be windows 2003, but the domain which should use DFSR required all the dc in 2008.
Follow the link below to perform migration of the FRS to DFSR.