Animal Handler now increases AP by 30%, up from 25%. Your numbers from the OwN description reflect the buff, so I'm guessing this one just slipped through!

While I haven't mathed it out, the obvious answer to me is that while haste is devalued with T13, Serpent Sting still is a relatively low portion of our damage. Since in an ideal situation you only use SrS once in a fight, all you're getting from those two talent points is 10% more crit on your SrS. The 2% haste, on the other hand, does still affect what Cobras you're casting, your auto-shots, and your pet's auto attacks, all of which add up to more of a benefit. In a non-ideal circumstance, where there are adds with high health that you'd be using SrS on, or lots of target switching that lends itself to SrS dropping off the boss, it might be different, but that's not what FD models.

Just a quick correction there. I don't believe that haste effects your pets auto attacks. I tested that last night by looking at my pet swing speed, 1.6 and then removed all of my gear. The swing speed was still 1.6.

While it may seem obvious to drop ISrS for full 3/3 pathing, I am looking at a 0.2% dps difference in favor of doing that in a perfect patchwerk fight (ilvl 397/403 geared). In reality, you just have to add a delay of 0.25 seconds to 1 CoS over a 5 minute fight (with 8 CoS) to have lost that. With mean choice reaction* time being somewhere in the region of 0.3 - 0.5 seconds, the time of gain is outside human control.
Contrast this with a definite gain with a ~15 second response time to do one action at any time during that, and I dare say that both in theory and in practise, ISrS will give you a noticable gain over the 2% haste from Pathing.

* - Choice Reaction Time, as indicated by the Jensen Box, the time to recognize and react to a simple stimuli - a light diode indicating which button to push. By all counts some raid situations could be equal o this simple test, but most will likely fall into a more complex, and therefore harder and more timeconsuming, choice and reaction.
The specific times are taken from I. J. Deary, G. Der and G. Ford (2001). "Reaction times and intelligence differences: A population-based cohort study"

Haste definitely does affect pet swing speed, however keep in mind the pathing talent is ranged haste only and does not affect pet attack speed.

I looked at logs for our first few pulls of Warlord Zon'ozz to decide whether I should run BM with a Devilsaur or a Spirit Beast (our 10 man does not have another consistent source of the healing debuff). Three observations from the data from our first set of pulls:

Psychic Drain with Monstrous Bite heals the boss only 7.5 * damage done (compared with 10x without MB). In the later log of our kill, for example (where I did not use the devilsaur), the boss would have gotten 1.4M less healing (or 1.9% less boss effective health). That would have effectively been a 1.9% increase in raid dps, even though it doesn't show up on meters (ergo I should bring DinoMight in BM!).

Monstrous Bite does not have 100% uptime. It suffers from the "pet doesn't recast until he notices it's no longer up" issue. One of the bites in the log above happened just after MB faded, and it was 1.5 seconds before it was on the boss again. MB had ~80% uptime, so other sources of the debuff may be preferred. Monstrous Bite seems to take a GCD, thus potentially impacting casting of Bite. That's based on a manual inspection of this query, and finding a regular pattern of 1.5 seconds between Monstrous Bite and/or Bite. It also does no damage. Expanding around the above example, the GCD may also exacerbate the gaps in debuff coverage; e.g., the MB gap happens to be around a Bite GCD. Simc does not show any dps difference as a result of turning off monstrous bite (simulated by comparing a wolf and a devilsaur). It will take more examination of the results to determine whether that's because simc doesn't implement the current Monstrous Bite behavior or whether for example the reduction in bite frequency is sufficiently mitigated by pooling more focus for Wild Hunt.

Bizarre, I was at 2k haste, and completely removing my gear did not change the pet displayed attack speed.

Moved the last three posts to SQ/SA as it fit better there.

Just an item of fun from Dragon Soul as BM.

My Turtle successfully tanked Yor'sahj last night on 10 man. The misses were from an accidental equipping of a novelty trinket which dropped me substantially below hit cap. I didn't use the +15% health talents as was on a whim. Only 2 times did the boss turn towards the raid, it tanked from behind and no-one was near on threat. I was 100% on Yor'sahj.

Pet spec: Hunter Pet Calculator - Wowhead

WoL: World of Logs - Real Time Raid Analysis

I was looking at the Pet talents, specifically the Cunning Pet talent tree. It doesn't make sense to me to put more than 1 point into "Mobility" - your talent choice of 3 points of Longevity makes the cooldown for Dive/Dash 22.4 (70% of 32 seconds) seconds long. The first point of Mobility would lower the Dive/Dash cooldown to 14.4 seconds. Given that the pet Dive/Dash duration is 16 seconds, there's 1.6 seconds of overlap there.

Even without the Mobility Talent, the pet would only be non-dive/dashing for about 5.4 seconds out of 22.4 seconds. I don't know where I'd put the 1 (or possibly 2) free talent point(s).

(edited for correctness and clarity)

OP updated with the buff to AotH in 4.3.2 under the OwN description. I remember being poked about anothe rplace I wrote something about it last time, but I can't find it - I think I edited the area to not require updating in the future though.