So I finally got a character on beta to 90, and since the price of Jade Spirit was through the roof on my beta server, I snagged Windsong.
In my testing, Windsong has a ~20% uptime on each buff, rather than 15%. I don't have logs at the moment, so I'll see if my guild will give me WoL access. For the time being, others will have to verify this; I know the holy priest guide on these forums mentions the same thing, though.
(using Twintop's "before 8085 haste" stat weights)
Crit: 1500 * 0.2 * 0.4068 = 122.04
Haste: 1500 * 0.2 * 0.7546 = 226.38
Mastery: 1500 * 0.2 * 0.3751 = 112.53
Total value of Windsong = 460.95
Jade Spirit, meanwhile, actually has a 50sec ICD, as mentioned
here. Which means its equalized intellect value is 396 ((1650 * 12)/50).
This should mean, then, that Windsong is worth more DPS than Jade Spirit before 8085 haste.
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Windsong after 8085 haste (using Twintop's stat weights):
Crit: 1500 * 0.2 * 0.4358 = 130.74
Haste: 1500 * 0.2 * 0.4173 = 125.19
Mastery: 1500 * 0.2 * 0.4195 = 125.85
Total value of Windsong AFTER 8085 haste = 381.78
Jade Spirit value after 8085 haste = 396 (same as before)
Jade Spirit takes over as being better after 8085 haste.
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Pretty sure the math checks out. Anyone else able to confirm? Mind you, I don't have a hardon for Windsong. Just interested in what will give me the best DPS.