The notion of ongoing updates as they originally appeared, though, raises the question of expansions. Blizzard has released seven expansions in all. And while later ones like Legion or Battle for Azeroth would feel out-of-place within the Classic framework, it stands to reason that some players may want to experience earlier expansions--such as The Burning Crusade or Wrath of the Lich King--in the context of World of Warcraft Classic. Blizzard isn't committing to this, but also hasn't ruled it out.
Travel Time is what you will be doing the most of, thus talents or abilities that increase movement speed will likely have the highest impact on leveling speed.The more important concept is this: Shaving off seconds of downtime between pulls is equally valuable to shaving off seconds of In Combat Time. When you think about it this way, Damage Mitigation and Regenerative talents / abilities / stats have almost offensive properties and should potentially be valued equally to stats that increase damage.