The Default location is hereetc/emulationstation/es_systems.cfgWhen you add new emu make change through system they get placed in etc/emulationstation/es_systems.cfg
To use a custom es_systems.cfg place here\\retropie\configs\all\emulationstation\es_systems.cfg
I have changed some logos, reorder, genesis, etc.
Merge changes from etc/emulationstation/es_systems.cfg to \\retropie\configs\all\emulationstation\es_systems.cfgThis way also you won't lose your edits during updates.
<path>/home/pi/RetroPie/roms/atari2600</path>
As we can see it would be simple to change paths from here.
Conclusion
Not for me. I want my es_systems.cfg copied to external drive. Use fsTab Method.
My Custom Changes to es_systems.cfg
Sorting differentI have a scripts system.I have many flavors of Mame, etc.No ChannelfBasically mine is better and I want it to be part of the external disk.
So I do not want to use this on the sd card.
So fstab is better.