I've been doing some more research into my helm dilemma. Apparently the Chaotic Skyfire Diamond theorycrafts to about 40 damage.

So my choices remain:
Spellstrike Hood / Vengeful Gladiator's Silk Cowl / Collar of the Aldor

Stats  Spell   Cowl  Collar
Armor   145    409    164
Stam    28     59     30
Intel   12     23     35
Spirit  0      0      17
Crit    24     36     39
Hit     24     0      0
Resil   0      33     0
Haste   0      0      0
Damage  60     56     52

So the dilemma lies in the sockets. With the Diamond giving me roughly 40 damage from the 3% increased crit damage and the 12 crit rating equaling roughly 9 damage, the numbers get a little closer.

For argument's sake, I'll run the numbers just taking the hood switch into account.

Going from Spellstrike to Collar is:
+19 armor, 2 stamina, 23 intellect, 17 spirit, 15 crit, 0 resilience, 32 damage. -24 hit.

Going from Spellstrike to Vengeful Cowl is:
+264 armor, 31 stamina, 11 intellect, 0 spirit, 12 crit, 33 resilience, 36 damage. -24 hit.

Wow, put in those terms, one of these should be my new helm. Since both lose the same hit rating, we can ignore that stat. With 12 crit = 9 damage, 3 crit = 2.25 damage, we can wipe out the crit difference and pretty much the damage difference. That leaves it up to the other three stats which are going to be pretty situation dependent.

Cowl has 29 more stam and 33 resilience (PvP only) while the collar has 12 more intellect and 17 spirit. Since spirit no longer factors into evocations, it's a tough call. I use mage armor on most boss fights, so the spirit will come in handy there to keep my mana pool high and the 12 intellect also equals 180 more mana while the cowl offers 290 more health.

Now I just need to figure out how to make up the 22 hit that I'm below the cap. It'll probably just be some resocketing of my Spellfire set. As I'm reticent to sacrifice 20 damage on my gloves for 15 spell hit. Back to the drawing board.