I believe Watcher indicated that for every 5% you improve gear the mobs increase say 2%. So if there is a base iLvL as a starting point, the higher your gear gets the more powerful you will feel. And I think his math may be suspect there. Unless I have read it wrong. Please correct me if I did. Because there is only a 5% increase from 860 to 904. So the health of a mob would be relatively static.
Let’s say he meant for every 5 iLvLs. A mobs health increased 2%. A mob at 1 million health would have 1.44 million at level 870, near 3 million at 890, and 4.3 million at 900. A player in 860 gear pulling 150k would need 7 seconds to kill a mob. One in 900 gear pulling 700k DPS needs 6 seconds. Seems pretty close and balanced. However. That is assuming a player can burst immediately to those levels, the disparity occurs between the different classes. Can a Mage stay alive long enough to burn the mob down wearing cloth, a Plate wearer can take the beating, but also has the high damage to go with it. This also explains the tool tip for Shadows Artifact weapon giving you reduced damage when creatures are within 12 yards.
What will make this difficult is players with non optimal gear, will have a much harder time than those in BiS heroic or higher raid gear. Equip bonuses, gems and enchant will mean the difference between killing multiple mobs in a few seconds, vs someone havingvto single target in 15-20 having to heal up after each fight. I can see where groups of 5, will quickly make the zone a joke over anyone having to go solo.