Originally Posted by Braque

This seems like muddled thinking to me. The trade off is the same no matter how many people do it. You still drop 81 healing and gain X mana/5s per person. It is in no way made better or worse by changing the number of people in the group who have it. The per person gains and losses are identical.

The "its better if everyone has it" is just psychological. Because 81 healing is a "selfish" enchant (it improves the performance of the raid by improving the performance of the one individual who has it in his role). Where as Spellsurge benefits the performance of the whole party (assuming the whole party is a caster group), so the individual only "feels" the full effect it (as an individual) has if all the other in the party have it, because that's the only way he'll get his "fair share" of its effects.

EDIT -> Added explanation:

To explain better this psychological effect:

Assume that the benefit to the RAID of +81 healing on a healer is 5 points.

Assume that the benefit of the mana returned to 1 person from Spellsurge is 1, so that in a 5 mana user group, the total benefit is equal (I know this is a point of debate, but its a useful assumption to simplify the maths that explains the psychological effect).

So, consider group 1, players A to D have +heal, and E has Spellsurge.

benefit
+heal | SS regen
A) 5 + 1 = 6
B) 5 + 1 = 6
C) 5 + 1 = 6
D) 5 + 1 = 6
E) 0 + 1 = 1
Total 20 + 5 = 25

Players A to D feel like they get most of the benefit from their own selfish +heal enchants, and E feels like everyone is outperforming him and he wasted his time on a crappy enchant.


So, consider group 2, which has stacked Spellsurge:

benifit
+heal | SS regen
A) 0 + 5 = 5
B) 0 + 5 = 5
C) 0 + 5 = 5
D) 0 + 5 = 5
E) 0 + 5 = 5
Total 0 + 25 = 25

Everyone feels the full benefit of the Spellsurge enchant, but the over all contribution it brings per person is the same. You should be able to see now that if the enchant is good (or not), stacking on multiple people it does not make it better.