So, in my journey of discovery that I've undertaken this week (what, didn't you know?) I've come across a few references where people compare FSW with Tier 4/5 gear, favorably.
So. Let's compare.
a. Shadow's Embrace / Spellstrike Infusion vs. b. Voidheart Rainment vs. c. Corruptor Rainment
(I can't get wowhead to pop up the cool little things, so you'll have to click!)
Now, the nifty thing about those links is they sum them up for you! Most of my work is already done. Woot woot.
The reason I list Shadow's Embrace with Spellstrike Infusion is that likely if you're sticking with those, you'll have both. Versus if you go full T4 or T5.
Now, I can't make nifty tables because I'm an idiot, so I'm going to go stat by stat comparison. Roughly.
Example: Longer Name: a. FSW/SI (35 letters) > b. VR (17 letters) = c. CR (17 letters)
Armor: c 907 > b 821 > a 734
-- armor is useful, but not essential for a warlock that isn't tanking.
Stamina: c 240 > b 183 > a 94
-- it's to be expected that the higher tier armor has more stamina, but of note is that the difference between stamina between B and A is almost double. In some instances, well, a lot of instances, you need a MINIMUM amount of stamina to survive. Most warlocks don't have an issue with that, but it's still something to keep an eye on.
Intellect: b 157 > c 146 > a 64
-- in this instance, B has more intellect than C, but only barely. But C has more than double A. Intellect increases your spell crit chance, not merely your mana pool. And while life-tap and dark-pact mean mana-pool-schmana-pool, they do nothing for your spell crit chance.
Healing: c 248 > b 203 > a 64
-- EDIT: Thanks to /emofire, I look like a moron! No, honestly thank you, Emo. :) So, according to WoWWiki, drain life, etc, does not benefit from +healing. So, does this only apply then to health funnel? What does it apply to? Do our bandages get a buff? Why the heck does our Tier armor have +healing? ... is it for those of us who want to secretly be shadow priests? Give it up, you can't heal anyone!... ahem.. So overall importance, depending on just which of our abilities it applies to (health funnel and bandaging??)... who the heck knows. I don't. Anyone?
Damage: Shadow: a 271 > c 248 > b 203; Fire: c 248 > b 203 > a 92; AVERAGE: c 248 > b 203 > a 181
-- This is the one place where, IMNSHO, A has a clear advantage over the others. You're a warlock. Unless you're destro-specced, (even if you are!) you do a lot of shadow damage. It's what we are. We're shadow-mages (only much cooler). However, it's boost to FIRE damage is pitiful and unless you're completely removing Immolate from your DoT rotation (some afflocks do), you're gimping yourself. I suppose destro-locks and firelocks possibly go Spellfire tailoring.
Spell Crit: c 88 > b 66 > a 50
-- If you're truly an afflock and you believe SB is for weenies, then this stat means nothing for you. However, even an afflock does a vast majority of their damage from SB. SB can crit. So, not so stupid a stat to look at, is it? The FSW set has ZERO spell crit. All the spell crit in this information comes from the SI set.
Spell Hit: c 65 > b 44 > a 38
-- Everyone needs spell hit. We all know the magic numbers. FSW set has ZERO spell hit.
Sockets: a 12 (2R, 5Y, 5B) > c 8 (6Y, 1B, 1Meta) > b 7 (3Y, 2R, 1B, 1Meta)
-- Though it lacks a meta socket, the sheer amount of gems you can put into set A makes it very customizable. A Great Dawnstone supplies +8 spell hit. If you ignore socket bonuses, you could get 96 spell hit in A, 65 in C and 56 in B. A Runed Living Ruby supplies +9 damage. Do the math, I'm lazy. Obviously, the more sockets you have, the more you can boost your gear. It's a nice versatility that so far, IMNSHO, is a saving grace of the mixed A set.
Set Bonus: There is no real rating for this, as the bonus of the set bonus varies from spec to spec and situation to situation.
A offers the chance for 92 spell damage for 10 seconds (SI) and 2% of shadow damage returned in the form of health (FSW). The FSW set bonus was rather nice to have when I was hateful bolt soaker in Kara and when I was farming, but personally, I'd rather have higher overall health and just siphon life.
B 2 pieces give you 135 fire or shadow damage chance, 4 gives your corruption and immolate abilities a 3 second boost in duration.
C 2 pieces gives your pet 15% of your damage in the form of life (hello demonology!) and 4 pieces cause your SB to increase the damage of your corruption by 10% and your incinerate to increase the damage of your immolate by 10%. (affliction or destruction)
IMNSHO, 2 pieces of B is better than 2 pieces of SI. What's really nifty if you could combine the two! Legs and Head of SI, two other pieces of B... then you could get a boost of 217 spell damage (fire or shadow) at any given time. Wouldn't that be nice?
I wish I had four pieces of C, since I'm a big fan of corruption. :)
Anyway... I guess this post could have come across better, maybe I can learn to put in a table and clean it up.
I suppose if you're looking in terms of just overall shadow damage and versatility, FSW/SI is the way to go. However, you take a hit in stamina, intellect, spell hit and spell crit and fire damage.
The nice thing is... my gear is mixed and matched! I'm wearing the FSW boots, T4 head, gloves, chest and legs and T5 shoulders. Though I've lost the FSW set bonus and obviously am no longer wearing the spell strike set, I evaluate gear on a gear by gear basis and upgrade to whatever is better, taking into consideration things like set bonuses and the like. It's a very individualized situation, where HOW you play and WHAT spec you play changes what gear works best for you. You don't HAVE to stick to only T4 or T5 or FSW/SI. You can do what I do, some T4, a T5, some FSW...
Maybe I'll make my first visit to Dr. Doom or Boom or whatever his name is with a few changes of gear and see what works best for me.