Assuming your guild has 25 good players and are always available for either 10 or 25, which would be easier for Ulduar?
I have been running Ulduar10 and it seems to me that it's pretty difficult in the 10man version. Whenever a player dies be it a tank, heal or dps, we will certainly wipe. There isn't any room for mistake especially in a progression type of raid.
What do you think? I have a feeling that 25 is easier as we can tolerate a few deaths and still able to kill a boss.