http://graalonline.com/skills/stores/upgrade
If you actually read what they advertise:
"Rent a server and build your own online game with Developer Gold!"
"Developer Gold for 6 Months (Server Renting)"
"Developer Gold for 12 Months (Server Renting)"
No where does it say it gives you access to other servers.
However I do think there is some merit to Developer Gold also granting you Gold subscription status.