After far too long, we did it. Everything went as planned.
We had a full 25 people in there that could play at the required level. No scrounging around for someone to fill this or that roll, and no under-performers.
Wrath is not an easy expansion from a guild management point of view, and the length of time we took on Yogg is a testament to that. I've seen more people lose interest in raiding faster then ever before, and replacements (generally) only slowly live up to the shoes of the departed. I don't know if players new to WoW as of T7 will ever be able to develop the finely aged skills of those whom were punished by challenging content repeatedly in the previous six tiers - T7 was like trying to sharpen a blade on a sponge. I see some people that show great promise, but it's taken a long time to get our hands on them.
That, and content isn't exclusive. Once upon a time, we could have 10+ people on standby, knowing that we were one of few guilds on our server that could show them past 4/5 Hyjal 3/9 Black Temple. Now talent is spread out over twice the number of twenty-five man guilds, and countless ten man's (which can let people "see" content in an even less demanding fashion). There is little reason for a person to join a guild that can't give them a large majority of bosses each week, forcing guilds to run on skeleton crews, and causing flexibility issues.
I don't know what the future of the twenty-five man guild is, but it's been a rocky road in Northrend. We'll certainly stick to it, but I wonder how rough Blizzard will let things get.