Your physical crit rate and spell critical rate are determined by different formulas. Crit rating contributes to both. Agility contributes only to physical crit rate. Malice and CQC only contribute to physical crit rate. So maybe I misunderstood your question, but there is no conversion of critical hits between your physical and spell attacks.

As for the relative value of AP and agility, to some extent there are considerations to which you are alluding, meaning that for high crit to be worth the bang, your base damage has to be high enough. However before this effect kicks in, another more important effect takes over. There is a crit cap that determines how much of your crit rate for autoattacks is actually possible. The thing is that in the autoattack hit table, crit is second to last segment. First an autoattack can be dodged, then it can be missed, (omitting parry and block since you should be attacking from the back), then it can be crit and whatever is left of 100% is your regular hit. So as your crit increases holding everything else constant, first you will end up in a situation where you do not have any hits at all. I.e all your attacks are either misses, dodges or crits. Then if you increase your crit further, you won't actually get any extra crits, since a certain percentage of your hit table is "reserved" for misses and dodges. This only applies to autoattacks, but it still takes a toll on the efefctiveness of crit rating and agility, so it becomes worthwhile to gem AP instead of agility.

So short version is yes in 3.3 and even now in some situations, "there is enough crit" but not necessarily for reasons you provided.

P.S. there is some evidence that there is a range of the hit table that is guarranteed for hits the same way it's reserved for misses and dodges before crits, which can further limit the effectiveness of crit rating and agility above and beyond what was previously known.

No there is no rollover of crit from physical to spell.

Soft cap normally refers to a situation when you cap during the duration of a proc, for instance you can reach and armor cap soft cap when an armor pen trinket such as MR procs. So for hit and expertise there is not relevant soft cap since there are no worthwhile trinkets that proc hit or expertise. There is however a hard cap for each which stops the misses and dodges respectively. Then your attacks can only be crits and hits. But that's not when you typically hit the crit cap. Crit cap normally occurs when your hit rating and expertise ratings are low, so a big portion of the hit table is reserved for misses and dodges, which does not leave enough room for all the crit rate you have. The exact formula for crit cap against bossesis 100-dodges-misses+4.8%, where 4.8% is physical crit depression against bosses.

Spell crit does not have a crit cap as crit roll is done separately from the hit roll. First you determine if a poison attack lands, then you roll again to see if it were a crit. Thus you get benefit from crit rating up to full 100%. Actually possibly even more since there is a spell crit depression of 2.1-3%; however, noone tested if 103% spell crit will completely eliminate spell hits. It could be that 3% of landed spell attacks against a boss are always reserved to hits.

Mavanas is actually missing one important information trying to explain it to you, and the main reason why theres a crit cap. Glancing blows, which makes up for 24% of the white hit table.

Ah I knew I was missing something, thanks Killme. Of course another 24% of the hit table is reserved for glancing hits, which is why crit cap is so likely to see with our current gear and more so going forward. Also if you start attacking your target from the front, blocks and parries also push crit out of the table, so if for some encounter we are forced to attack from the front (Kil'jaeden comes to mind), that's something to keep in mind as well.

I'm a well-geared arpen soft cap rogue with minimal Mutilate experience. I've been looking at how arpen combat rogues can transition to Mutilate come the patch, and was wondering if there was a handy-dandy "if/then" clause that can help narrow down when the transition might be appropriate.

By an "if/then" clause, I mean something akin to the familiar "If X, then break 4pc. T8. If Y, then spec Evis-only." Not a hard and fast rule, but a generality to aim for so that when we start spreadsheeting stuff, we aren't playing with too many variables.

There's not really a large difference between combat and mutilate gear.
Looking at your gear, all you'd need to do is gem AP/Haste and swap Bloodfang Hood for T9, Duskstalker for either T9 or Spaulders of the Snow Bandit, Dexterous Brightstone Ring for Normal Callous Aggression (or Planestalker HC).

Algalon Bracers are a slight upgrade over Swift Death.
The Diplomat should also be a very small upgrade over Crimson Star.

In general 4pc is pretty bad for both specs (unless it's the 258 variant).

I have a question, please ignore me if it was answered already:

With the two t10 tier bonuses and granted enough Ar. Pen on gear is it possible that HaT could become viable again?
I understand it largely depends on fight mechanics, but if we ignore them and only look at the fore mentioned factors, could it be the case of the HaT return?
I am especially interested in a build with the "Improved TotT", so if anyone has tried it on PTR please share your thoughts.

Thanks

I remember reading awhile ago the for the mutilate weapon swap spec that relentless strikes was better then taking oppertunity is this still true or was it ever and did i just imagine reading this and oppertunity 2/2 is better thne 2/5 relentless strikes.

Wait so if your dp procs on the target again you also have to do a check against PPM for your mh poison procing? I always thought it was just if dp was proced on a target with 5 stacks of dp your main hand poison would go off instantly no matter what, so the faster your offhand the better because dp is percentage based only.

What you were thinking is exactly what he was saying.

You will want to go for IP/DP and 20/51/0 if you choose to stay combat. What spreadsheets say however is that mutilate will be 1-2 k ahead of combat in terms of dps.