I'll be more specific with what I meant before. Some of the things in this post is wrong or out dated, in my opinion. One example of out of date is someone was theory crafting still with Arcane Shots between Explosive Shots. They now work as magical dots and won't be clipped if you re-apply after the 2nd to last tick. An example of "Wrong" is the idea of Lich King enchants being better than Cata ones because of the agility. 22 agility is 44 AP and I believe .07% crit. More AP with different specs, but with survival, it's 24 agility for 48 AP, plus 10% AP = 53 AP? Roughly.
According to femaledwarf.com with my current mix of T14 and T14 heroic gear the 65 mastery enchant adds 12 dps over the Cata one. The 65 crit to cloak enchant adds a whopping 16.1 dps over the Cataclysm enchant. I consider both of those to be small enough to be statistically insignificant.
Edit: One thing you may be forgetting is that Survival (and BM) have talents that increase the agility enchants in addition to the raid buffs which increase them.
=Lock and Load=
With damage over time abilities now refreshing without wasting a dot, "interleaving" a cobra shot between procs is less viable. Instead we can more quickly use our explosive shots without wasting charges. Simply spamming Explosive Shot will result in 8 ticks, with 1 lost. Before 4.2 this would have been 7 ticks. If you wait a small fraction of a second after the 1 second GCD, it should be sufficient to get all 9 ticks quickly. This would be 9 explosive shot ticks in about 3.3 seconds assuming you wait 0.1 between each. This is almost always the best usage on single target, although there may be times when filling in an instant cast ability such as kill shot is worthwhile.
I'm not sure what you find wrong here. If you spam 3 straight explosive shots, the second will not clip the first but the third will cause clipping. If you read the last several pages you'll find a discussion on the subject.