Part of that will be relearning MM PvP. There are a lot of fundamentals that are the same between all specs, like scatter-trapping, disengaging, ect. These are all Hunter basics, so I want to focus on spec specific differences.
Kill Command vs Chimera ShotKill Command is boosted well with 10% extra crit from Improved Kill Command, plus a 20% damage boost from Killing Streak. They synergize well, but Killing Streak procs too randomly, and is often wasted. I look forward to the changes in Mists.
Chimera Shot costs slightly more focus than Kill Command after taking Efficiency (44 focus) which is hardly noticeable, dazes the target with Concussive Barrage, applies Hunter's Mark with Marked for Death, heals you for 5% of your health, and refreshes Serpent Sting. Chimera Shot is a friggin Swiss Army knife of an ability. Granted, the Serpent Sting refresh is not a major advantage compared to Cobra Shot's more frequent refresh.
Winner: Chimera Shot
Cobra Shot vs Steady ShotCobra Shot is magic damage and refreshes Serpent Sting. It's plain and simply a great filler shot.
Steady Shot generates 6 extra focus on targets at or below 25%, deals physical damage, causes a bleed with Piercing Shots, and is guaranteed to crit on targets above 90%, and boosts attack speed when used twice in a row with Improved Steady Shot. Steady Shot is also kind of a Swiss Army knife of an ability, but it's less amazing than Chimera Shot. The bleeds can be problematic for CC, the physical damage is anemic, the attack speed boost can be a challenge to keep up, and the extra focus from low health targets is an intermittent advantage.
Winner: Cobra Shot
Bestial Wrath and Fervor vs Readiness and 3 minute Rapid FireBestial Wrath breaks fear, increases damage done by 10/20% for the Hunter and their pet, respectively, and reduces the focus cost of abilities, effectively negating the need for a filler. It's low cooldown time of 1 minute 37???? seconds make it sort of a part of the BM rotation. I use it in conjunction with Synapse Springs. It's Big Red Pet. It rocks!
Fervor I typically use just before or after a Bestial Wrath to maximize it's return. It's not a lot averaged out, but it's good for burst.
Readiness is less familiar to me in a PvP setting. I'm more accustom to using it in PvE solely to double up Rapid Fires. In PvP it will be much more situational, and I'm totally a newb again.
3 minute Rapid Fires, doubled up with Readiness, is very powerful.
Focus Fire vs Improved Steady ShotFocus Fire is BM's haste buff, and builds up quickly. It only requires 1 button press every 20 seconds or so. I think it's much easier to keep up than ISS. BM is already a very focus positive spec, so it's not a huge deal, but it helps noticeably.
As I've already stated, I dislike ISS's difficulty. It's more difficult to initiate, as it requires two slow casts before activating, and it's more difficult to maintain, given it's short duration.
Winner: Focus Fire
Intimidation vs Silencing ShotIntimidation is a great general purpose ability, affecting any target not immune to stuns, melee and caster alike. I typically would use it just before a Kill Command, especially one boosted by Killing Streak, to insure the target is in range. As a generally less-used ability, opponents may also be thrown a bit off balance by it. The minute cooldown is short enough to be useful, but long for a 3 second duration ability.
Silencing Shot is a Hunter's most reliable interrupt. Certain pets can bring an interrupt, and Scatter Shot/Wyvern Sting/Intimidation/Pet stuns ect, effectively work as one if timed right, but Silencing Shot has the added advantage of a 3 second silence, of course. It doesn't compare well to a Mage's Counterspell (7 seconds) or a Priest's Silence (5 seconds), but it's low cooldown of 20 seconds and synergy with Readiness makes it very competitive.
Winner: Silencing Shot
Crouching Tiger, Hidden Chimera vs PosthasteCrouching Tiger reduces the cooldown of Disengage by two seconds when hit by a melee attack, and the cooldown of Deterrence by 4 seconds when hit by a ranged attack. I've not personally seen a major advantage to the Deterrence reduction, but the Disengage reduction is very noticeable when two or more melee are targeting me.
Posthaste gives a 30% speed boost for 4 seconds after Disengaging. I find this to be mostly wasted if I'm kiting a player while staying engaged, but it's invaluable for escapes.