Also, once you go MMO, you break the environment.
Stargate is small teams doing missions. Occasionally multiple small teams doing the same mission together.
Stargate is not thousands of people all doing quests and gaining XP to let them do more quests.
What they need to do is a sandboxed FPS with coop play.
Imagine Left 4 Dead mixed with Stargate with a lot of flexibility. 4 man team, go to planet, do stuff, return to base.
The dial from Earth would send you to the right place - Walter's not silly.
On your return, you have to enter the correct address. If you put in an invalid one, you get no connection. Put in the wrong planet and you load that map and go there, probably with the game chastising you for going to the wrong place (Go to Ba'al's homeworld and get violated by all his Jaffa, etc)