its a great shot for the vanilla and tbc experience, with different kind of servers like instant 60(70), 12x leveling and 1x Blizzlike leveling.
But the servers are quite old, so most guilds have the endgame content on farm and best in slot equipment.
I recall checking feenix out but I don't think I signed up there. I don't recall; I tried several when I was looking a while ago.
Even in the real game, you had your established guilds that had the raids on farm. Or they had their team and was working on progression. So that isn't much different really.
I was mainly in pvp. But I also did some gdkps raids, there are almost a few of them every day.
in gdkp raids you can bid on items with gold and you get also a split of the gold pot in the end, thats a nice way to farm gold and equip.
Most of the time I played on the warsong(12x vanilla) realm, its the most populated server of the feenix realms.
You should just try it out yourself.
You don't say how broke the world is, I recall feenix has issues but that was a couple years back.