I think balancing the Cov and powers with class balancing is whats been tricky, as well as the maw being empty and im sure they felt.. 3+ more weeks to continue to balance the Cov and such would be worth it.
All it takes is one or two over powerd to pull a class into .. needing some kind of nerf. which is never wanted. from a class standpoint. as much as i want it to drop on 27th, pushing it back 3+ weeks makes it a more polished game. clean up some quest bugs, instance bugs. and continue to work on the balance issue... is only better for everyone that plays wow. frustration with feeling like your playing a game with a broken leg or arm is frustrating. and not fun, from casual to hard core. as well as some of the questing xp and fine-tune the path from zone to zone. which is another bug..
So. i am looking for it .. earliest...mid to late Nov. latest...early to mid Dec. I would say. if it was only a week needed they felt they would have NOT delayed. so im guessing they needed or decided they needed 3+.. 3-5 more weeks of fine-tuning. all in all, we get the pre-patch on 13th. so they may still make patches for that for class stuff, but, the core team can move forward.. and then when its ready. they will post a date. and then schedule the pre-patch events to get us ready for a polished SL game launch.