Since you cant enter without a premade 8 at minimum, You would only ever be grouped with OTHER premade 8s.
So 9 times out of 10, you will enter with 2 other FC crafted groups. Sometimes you'll enter with a RevToll shout group.
The issue with queuing as a 24 man alliance is likely due to the current cap of 8 players to a Party. They probably want a create a proper UI for forming such a group, or to limit it to Alliance only content.
