Here are some impressions from the few runs I've done so far with my new guild:
* Raid setup is fast - while typically in my older guild, even though we were doing only 10-man raids, it took us a long time to get started. According to guild rules we were supposed to start invites at 19:45 server time, in reality we would still be missing people at 20:00. Many times our raids would start only at 20:10 or later - sometimes much later. With the new guild, you are supposed to show up online at 19:30, even though raid invites are at 19:45. Invites start on time and no special effort is made to make sure people come, e.g. asking if people need a summon. People are just expected to show up on time at the Ulduar entrance, and typically they do. Yesterday was a very good start for example - invites were on time and raid was filled by 19:50. I had to go AFK for 5 minutes - by the time I got back (19:55), most of the area leading up to Flame Leviathan was already cleared... by 20:05 FL was down.
* Optional (non-tier loot) bosses are skipped if possible. In my old guild we did FL, followed by Razorescale, XT and Ignis (who is IMO the hardest boss in the first wing). Only after first wing is cleared did we use to continue to the second wing, where we would go for Assembly first, followed by Kologarn, and the bosses after him. My new guild takes down FL, XT, skips Razor and Ignis and the Assembly and goes right for Kologarn, opening the way to the harder bosses. Last night we wiped some on Thorim but had we taken him down quickly and managed to do Freya, we would have had all of today for Vezax and Mimiron and Yogg-Saron - bosses which are still hard for the guild. I like this method of clearning Ulduar and I'm sorry we didn't think of it in my previous guild. Live and learn.
* Minimal setup time before boss fights - if someome doesn't know tactic it is explained briefly but the sentiment seems to be "lets do it and if we wipe at least you would have seen the fight which is better than a long explanation". On the one hand I like this, spending 20 minutes in my old guild explaining tactics to people new to the boss was something I always found very annoying. However I think the new guild takes this minimal setup approach to an exterme, for example, there is almost no healer setup done, except when required by fight mechanics (e.g. split up the group on Razorscale to 2 sides or gauntlet and arena group on Thorim). On the one hand this saves time, on the other we have wiped in the past due to healing problems... well, time will tell what is the correct balance.
* Back to the DKP - a 10 man raiding guild is small enough to just roll on loot, I think (I hope I am right) that after a week or two all people got at least some loot from bosses. In the new guild they use a DKP based system, on the one hand this is good due to the inherent advantages of a DKP system (the more you raid the more chances at winning loot), on the minus side it seems to make people only care if they have enough DKP, some people I've seen out-bidding on items even when it was clear the other person bidding needs the item more.
* We have nothing to be ashamed of - basically the people who came over from the old guild are 1 DPS, 1 tank and 2 healers (well and 1 social :)). In tems of doing your job in the raid, knowing to "get out of flames" and being high on meters I think we are all doing a great job. Our DPS has been as high as 3rd place, incredible considering his gear (mostly 10man Ulduar). On healing meters we are lower but healing meters in any case don't measure everything and the important thing is that the raids we are in manage to take down even hard bosses (there are some hiccups but those will go away as our gear gets better).
Oh yeah, last point - it feels good to be raiding regularly again :)