Nah, Beta 4 still isn't done, Sapien is being gay on and off.
It's more of Build 4, but still. A lot of changes are going into effect, mainly some stuff to make the Camo Hunters harder to fight, and the Shielded Hunters easier to fight.

Oh, and some bios of the enemies you will encounter:

Covenant:
Special Ops Hunter:
Normally sent on Search-and-destroy missions, these guys are walking tanks. With impenetrable black armor and the strongest Covenant Shielding systems, only the strongest Hunters can don these massive suits. On their arm is the strongest version of the Covenant fuel rod, the Anti-Aircraft "Scream" Fuel Rod Cannon. Despite it's name, this fuel rod doesn't home; instead, it is 10 times as powerful as a normal fuel rod blast, and the Hunters in the Special Ops Armor can track and lead with 97% accuracy, giving them the capability of bringing down aircraft in 1 or 2 hits.

Assassin Hunter:
Sent on missions where stealth is a must, these Hunters are silent as the grave, managing to make no noise whatsoever when they pass. They don white armor and the same active camouflage technology the Elites do. They are normally found with or near camouflaged Elites, so be on your toes.