There are only 3 DPS in Heroics and only 5 DPS in 10-man raids..
OT: I did some tests on the Heroic Dummy, each test running until I reached 3 million damage done. I am MM, was using a wolf, was hitcapped, and was alone.
Before reforging all my crit (where possible) my stats were 66% crit, 20% haste and basic Mastery. This netted me an average DPS of about 7-7.5k
After reforging my stats were 53% crit, 20% haste and a 40% chance of proccing Wild quiver. My DPS went up to about 8.5k after this.
So yes, Mastery looks like it is awesome at the moment, though this will probably scale down once we start leveling.