It's always recommended to go to the latest version to clean up bugs and vulnerabilities. There was a buffer overflow found in an earlier version of SEPM, check here:
https://www.symantec.com/security_response/securityupdates/detail.jsp?fid=security_advisory&pvid=security_advisory&year=&suid=20130618_00
Upgrading to the 12.1 RU3 fixes it.
I would suggest upgrading if you can.
Best practices for upgrading is here:
http://www.symantec.com/docs/TECH163700