With the expansion coming with new content making us turn back to the XP grind. It has been said that its gonna take some time to level from 60 to 70. around 120 hours is one estimate and another is the same time it took from 1-60.

When leveling to 60 and at the High-End instances (Scholo, UBRS) pure PvE specc's did not make that big of differance. It (IMHO) did not make differance in MC either, only made things faster and smoother. Now I can't say for sure since my first char entered the game rather late (hit lvl 60 Nov. 05).

Therefore I assume that it will be the same while leveling to 70 and in the initial lvl 70 instances. That it will be OK with a grind specc as long as you do the task given in the group ie. a shadow priest could (and should if only healer) be healing.

Would it be a true statement that certain talent speccs will not be required in the race for lvl 70 End-game instances?

A thread to compare talent specs?

No.