Back than Blizzard “hotfixed” exp gains in Northrend to prevent people from leveling faster in Halls of Lightning etc. than doing Quests in the Level 80+ Zones.
Proof is an old Video Kripparian did:
2 days before cata launched you got 90% less exp expect in the new zones!
Are you planing on doing the same thing in cata classic?
If the other expansions are something to judge by, they release things based on the last patch balance and bug fixes, then just release the base patch content.
look at the state of the beta who cares about 4k xp mobs in Hol?
xp is so fast there are better thing to do
server first is going to be the mob tagging anyway in the hyper spawn probably like 5 6 hours after release
edit: thank the poeple for spreading out and not having 100% of the server chasing 5 mobs or 2 piles of earth in hyjal
any update?
lol, you’re expecting a reply from blizz? They don’t reply to any of our questions.
why nerf something efficient and (dare i say!) fun?
lmoa you know the fun part Cata dungeons give more XP , and some other spot even 7 to 8 million xp and hour keep crying for Hol server first will be done in around 5 hours and its not going to be Hol or some other **** Wotlk dungeons 
and spreading population around different locations is not bad imo
but yeah waste time to fix stuff like this when not even the most basic stuff is working on beta server ^^
so, 80-82 is fast, but 83+ is a lot slower. 83 is 5m xp. I think 80 was only 1.5m. I spammed dungeons to 83 but now it looks like I’ll have to quest to get to 85.
83 is 4m xp in Hol that is like 1hour20 i dont think thats long
84 is 5.2 so even that is less than 2 hours
85 is 9m there you are for 3hours
but you can go black rock and it will go up faster since you get almost 4m xp/hour
Should look up the XP requirement from 89-90 in MoP.