First, we only raid 4 nights a week and only require 30pct attendance for a rolling 30 and 60 period to maintain membership. That means that people don't burn out like they do in the more aggressive raiding guilds. If an individual has RL issues and needs to miss a couple weeks of raiding, it's no problem for us. We maintain the numbers to continue on, and they won't suffer any negative side effects as a result.
Second, we set and achieve gear goals for each expansion. We don't just plow through the content to say that we were first. We take care of our members. This ensures that every member is prepared to be successful in new content, not just the top dkp. For example, We farmed CoA every 5 days for 14 months to ensure that no member gets left behind. We've killed OMM 34 times (also server first).
Third, we don't skip progression or skip around in content. We work through the expansions in order and with purpose. When we reach a viable farm zone, we milk it dry while we work on the next expansion's progression. This chart is a little dated but I think you'll see what I mean.

I'll add one final point about our pace and your perception of slow. Gale wasn't around when the server opened. Gale started raiding WToV in March of 03. We've since established ourselves as one of the premier raiding guilds on Tunare. I don't think many will argue with that. We're successful because we take care of our membership, all the way down to the lowest attendance member.
As for the quality of our membership. I'm not sure what metric you would use to determine. I believe our reputation on Tunare should speak for us well. I've heard rumor that we come off a little snooty, but I think that is to be expected any time you have an organization that is both successful and inwardly focused. Shrug.
As for guilds across the server. I'm pretty sure they are all doing well. We've got a number of active raiding guilds that are all successful. Talisman is working through Ashengate atm. Infinit (public) is working on Frostcrypt. Dai Shan, and Gale of Destruction jsut got into Deathknell (we're a little behind but we're catching up

How do you define success?