Improved Hunter’s Mark vs. Efficiency
The question of choosing between Improved Hunter’s Mark (IHM) and Efficiency comes down to your placement in a raid situation.
Let’s take a look at IHM first. The talent at Rank 5 “causes 100% of your Hunter’s Mark ability’s base attack power to apply to melee attack power”. What exactly is base attack power? (Regular) Rank 4 Hunter’s Mark provides an extra 110 attack power to the ranged attacker and an additional 11 every time the enemy is hit by a ranged attack, up to a maximum of 440 attack power. Base attack power is the unbuffed attack power that is provided by Hunter’s Mark, not including the bonuses. Again, at Rank 4, this value is 110. Therefore, with Rank 5 IHM, everyone attacking that enemy has his/her attack power effectively increased by 110, not the maximum value of 440.
Rank 5 Efficiency allows for a 10% reduction from the mana cost of our shots and stings. Plain and simple.
Because the effect of IHM applies to the entire raid, only one hunter needs to have it specced in the Marksmanship tree. Having more than one hunter putting points into it would be a waste because the other hunters could be more mana efficient and putting out more DPS. In a raid situation, it is best to assign the hunter with IHM to mark the target to be melee’d. If there is a target that need to be taken down from ranged, have the other hunters mark them. It’s best to mark the tank’s primary target if you have this talent in the tree.
My suggestion is that if your mana pool is lower that most of the hunters in your raid group, you are better off choosing Efficiency over IHM. Have the hunter with the greatest amount of mana pool be assigned to mark the main target so that melee groups will receive a buff in attack power.
As a marksman, if you would like to choose Improved Hunter’s Mark over Efficiency, it is my recommendation that you have an unbuffed ranged attack power of at least 2000 when you’re at the point where you’ve been able to complete Karazhan and are starting to look at upper Tier 4 and into Tier 5 content. This way, when you are using Aspect of the Viper in a mana intensive fight, you will not dip below the 2000 mark and can still contribute a good amount of damage. You are also likely to have mana biscuits in a raid, so running out of mana in between trash fights is perfectly fine.
When being used by other primary specs (beast mastery or survival), it’s more of a matter of preference. From a beast master’s point of view, IHM can improve your pet’s attack power and DPS, and a 1:1 shot rotation is not as mana intensive. From a survivalist’s point of view, Efficiency can contribute to a more sustainable DPS when used in conjunction with the talent Thrill of the Hunt.