Shield enchant question (threat vs avoidance)

[Xeider]

Current armory The World of Warcraft Armory (http://www.wowarmory.com/character-sheet.xml?r=Detheroc&n=Gunk)

Planning on reworking gem slots when 3.0 hits since loss of defense eminent

[Formula: Enchant Shield - Major Stamina] (http://www.wowhead.com/?item=28282) vs [Plans: Felsteel Shield Spike] (http://www.wowhead.com/?item=23530)
(http://www.wowhead.com/?item=23530)

Currently working PvP honor to get [Merciless Gladiator's Shield Wall] (http://www.wowhead.com/?item=32045)

I have [Dawnforged Defender] (http://www.wowhead.com/?item=34676)

Trying to decide when I get the PvP shield... if I put the +18 stam on it, should I put shield spikes on the Shatter Sun shield for a threat generation for trash pulls?

Some quick comparisons if I was to do this... (all unbuffed stats w/ no shouts up)

with PvP shield w/+18 stam buff
17808 AC (62.78% reduction)
23.30% dodge
14644 Health
61 Hit (3.9%)

with SS shield w/ Felsteel
16868 AC (61.5% reduction)
24.25% dodge
14274 health
74 hit (4.7%)

another option would be to just buy another SS shield and put spikes on it... since they are not unique

Any suggestions/recomendations... hopefully the ZA shield will drop at some point... or I will get luck in a Grull PuG...