Hello Girls and Guest!
You asked how servers react to class themed guilds.
For our all hunter guild, Icecrown didn't know what hit them.
Most had no alts on server so took up herbalism and mining. The copper and peacebloom markets took months to recover and we quickly created the Dead Hunters Union Guild of Death Knights, so the baby hunters would have the 10 gold to level lock and afford things.
We were very All For One Everything For Everyone, and set up 7 more alt guilds to handle alts being server transferred in and profession materials, and especially bag making to supply the hundreds of hunters in the WHU.
We crashed the server twice on our first event, rocking up from Kharanos to Ironforge, with everyone's pet out and often a battle pet rolling in to catch the tram to Stormwind.
After that we made strenuous attempts to warn Blizzard when an event was coming up, and our projected route but still crashed Stormwind at least once, and Thunderbluff when we tried for the Horde Leaders achievement.
We got all of them except Sylvanas. It was an honor to fail to kill such an exalted huntress as the former Ranger-General.
In a way, having an all hunter guild was easy because we were all Hunters so the gear we needed was obvious. Engineering guns and scopes, leather then mail. Hunter glyphs.
We got very familiar with Wailing Caverns which is all hunter gear heaven, if you don't mind tight purple pants.
And of course, Pets. Petopia was our Bible and our Horde alt guild maintained Echeeyoki the white quested lion for the hunters to tame.
One of my fondest memory of WoW is escorting baby hunters through the dangers of Ashenvale to get a specific color pet that they had their heart set on.
Being in a class guild is different from other guilds in that we all had a passion for being a hunter. We could all help answer questions, we all knew the same jokes , we all knew the best pet for the DPS.
We were all great people, and I'm sure that other classes have nice people too, but we were worried about, you know, problem people, and we never had any.
Blizzard is big on class pride this expansion, and the pride was real.
You should start one and try it sometime.