Crimson Tempest should now stack correctly with Sanguinary Veins and Mastery: Executioner.

After this hot fix it looks like CT will not be part of the rotation as now the CT dot does not double dip from SV and Sub mastery.
Before the Dot would do more damage than it should but now that has been fixed

I was looking at shadow blades usage as assassination and what I found is that it appears that on fights of certain lengths it should sometimes be worth delaying the last usage of shadow blades until the target is below 35% (in cases where you won't be able to fit another if you don't delay).

I arrived at this by looking at the energy cost per combo point of mut+blindside rotation vs dispatch. While not under shadow blades, mut+blindside generates more combo points per energy than the dispatch rotation except at very high levels of crit (90%+).

However, while under shadow blades, the dispatch rotation is better combo points per energy than mut+blindside at all levels of crit.

Thus, it should be a slight dps gain to delay shadow blades until you transition to dispatch rotation at 35%. I am not sure how much of a gain this is however, but the effect is most pronounced at low and high levels of crit.

Here is a link to a spreadsheet with the calculations. I really want other people to check my calculations, since this is my first time doing something like this on my own.

Always keep in mind that SimCraft is a theorycrafting tool, not an absolute measure of some ideal goal to reach when raiding. The very nature of content being limited to a relatively low number of very specific fights makes the actual numbers vastly different from the simulated ones.

That being said, SimCraft does help illustrate potential problems in relative powers of classes/specs. Combat being behind by a significant margin could very well be a cause for concern. However, never forget to also make the transition from theory into practice - as you pointed out, the nature of the fights changes the actual results from their theoretical values, often quite significantly.

This does not only apply to cleave, either. There may be cooldowns to allign, or phases that require burst, or lots of movement, or any of a plethora of other factors that are not usually included in a basic SimCraft ranking. Blizzard knows this, and they are taking it into account when balancing specs. One could say that the very reason for the new talent system was this, the ability to adapt on a per-fight basis, lessening the impact of certain specs on a given encounter.

As to which spec is "harder" to play, that is very much in the eye of the beholder. Also, "harder" specs often leave more room for skillful players to craft an edge for themselves, which is widely regarded a positive thing. As I stated previously, I personally feel that right now, Rogues are in a pretty good spot concerning the variety, complexity, and difference in play style between their three specs.

The only beef that, in my opinion, remains, is the aforementioned cleave. As Aldriana has already noted in his excellent blog post, the existence of Blade Flurry skews results and preferences in a way that is way more relevant than the SimCraft margins between the three specs. If anything, we should be upset about that, not the small differences in relative rankings.

And as always, the verdict is still out on actual, live raiding. Once we get deeper into T14 heroics, and past the initial wave of nerfs/buffs that is no doubt to come at the start of this expansion's raid progression, I think we will re-evaluate. It may be too early to cry out, but I do agree that the situation as a whole warrants constant monitoring. And that includes all factors, not just SimCraft rankings!

(EDIT 9/29: I should note that I posted all the stuff below before I saw the 9/28 hotfix notes, which included an item stating that the alchemy stone should now be working as intended. The hotfix must not have been applied yet on my server, or perhaps require a client-side fix; I tried again Saturday morning and got the same results as below.)

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I am really new to this dummy-testing thing, so these logs from tonight might be useless. But I got the [Zen Alchemist Stone] and wanted to see what I could learn about its ICD by whaling on a dummy for a while. So I did -- as Assassination, on a level-85 dummy (since this was purely a proc test), sometimes in my Cata gear (including Landslide-enchanted legendaries), sometimes in the fashionable-but-useless gear I usually log off in (gear that, other than the new trinket, includes nothing that procs or applies buffs/debuffs). And maybe I just did a really stupid job of testing, but this trinket was behaving weirdly for me.

It seemed never to proc off of autoattacks. It seemed never to proc off Deadly Poison ticks. It seemed never to proc off Leeching Poison ticks. It seemed never to proc off Mutilate or Dispatch. It *may* have procced off of Envenom, and it almost certainly procced off Rupture ticks.

As the log link above will show, this was not an extensive series of highly compartmentalized tests; I basically just screwed around with stuff for half an hour just to see what would happen with various briefly employed approaches. But for me, in the particular gear/spec I was using, the trinket was not behaving the way it'd be expected to behave. Hopefully this is unique to this particular trinket and not true for other proc-based trinks.

Incidentally, I didn't remotely have a large body of evidence to work from here, but the shortest ICD I encountered in this poor series of tests was juuuust under one minute:

9/29 02:22:13.943 SPELL_AURA_APPLIED,0x0580000004760806,"Rfeann",0x511,0x0,0x0580000004760806,"Rfeann", 0x511,0x0,60233,"Agility",0x2,BUFF

9/29 02:23:13.776 SPELL_AURA_APPLIED,0x0580000004760806,"Rfeann",0x511,0x0,0x0580000004760806,"Rfeann", 0x511,0x0,60233,"Agility",0x2,BUFF

Yeah, the buff is called "Agility." Pretty sexy.