Quote (Redone @ Sep 9 2011 01:17pm)
Question. If you do guild only does it do anything other than only let your guild members join your party? I had heard rumors of better drops and more exp. If anyone can shed some light on this for me would be excellent

Taken from the LS Portal:
"The player also has a option to make the game Guild only, (this increases experience and drop rates, but only allows members of your guild to join)."
I can tell you from experience that the increase is not huge, and you might not even notice any difference, at least I don't always notice it.
Guild-only games can be fun just for the teamwork and friend factor, it's a lot easier to communicate with friends/guildies than it is with the general public.