The installation directory is entirely your choice. The default configuration of the agent is one that tends to be less visible/obvious to users in case you aren't wanting to advertise that the DLP agent is present. As such, the /Manufacturer/ directory is used by default in an attempt to keep users from getting too curious.
Many customers who plan to have the DLP agent much more visible (show the 'Scanning' dialog, notification windows, blocking prompts, etc.) will switch the default install path to something else (like '/Symantec/') to align with naming conventions of other installed software.
Either way, there is no impact on how the agent performs or operates.