i switched out some gear today for some new items and My gear score has not gone up but down a point
[Frozen Tear of Elune] for [Arcane Loops of Anger]
[Chalice of Benedictus](regular 10 man) for [Shriveled Heart]
[Conqueror's Circlet of Sanctification] for [Sightless Crown of Ulmaas]
now the only reason i switched helms was because i had to offset the loss of hit rating . Otherwise doing some research the loops of anger and Shriveled heart are both higher on the dps charts for both the offhand and the neck being significantly higher for their dps output.
other then the helms being more or less equal trade off( since i know gear score does not matter) just to replace hit the only thing that went down slightly was my crit rating and my int while my haste and my spell power both went up went up.
Also replacing the helm did not effect my set bonus since that was the only piece of T8 i had on and other then a lack of a meta gem in my new helm it seems that my gear score should still have gone up at least a few points due to the other 2 items that are supposed to be superior to the others i had before.(hence raising gear score for a shadow priest)