Using Arawethion's spreadsheet, I plugged in my stats in non-moonkin form:
3177 SP, 1106 crit (which is about 34% on the character sheet), 678 haste, and 294 spirit, 268 hit. The spreadsheet takes into account full buffs (including moonkin form) when calculating expected dps.
Things to note:
- Over soft-crit cap during lunar
- Obviously over haste/hit cap, not that it's anything special
- Low amount of spirit
So the result I have is 10617.66 dps using "Eclipse, MF/IS" rotation. Then I upped each stat by 1 point to see the resulting dps, and merely subtrated 10617.66 to get the difference in dps.
Since I'm over the crit soft cap, you can see that the value of crit dimishes under haste. Spellpower still has the strongest foothold. Spirit is just crap (oh look, it's about 30% the worth of spell power - how predictable). And Intellect... well try not to gem intellect.
Over haste/crit soft caps
----------------------
Default DPS: 10617.66
Stat DPS gain DPS Normalized
+1 spellpower +2.00 10619.66 1.00
+1 haste +1.28 10618.94 0.64
+1 crit +1.13 10618.79 0.57
+1 spirit +0.66 10618.32 0.33
+1 intellect +0.43 10618.09 0.22
I did some further stat tests too to see how each stat fared when under the soft haste/crit caps (300/900 rating respectively). I'm ignoring spirit/int for obvious reasons (spirit will likely still have the usual 30% the worth of spellpower as expected). Haste easily trumps spellpower in this scenario, but keep in mind that the 300/900 rating assumption is a bit sketchy. However, it gives us some insight as to the stat weights. So if you're just gearing up, keep note that haste has equal, if not better, value than spellpower and crit.
Under both haste/crit soft caps
----------------------
Default DPS: 9738.03
Stat DPS gain DPS Normalized
+1 spellpower +1.83 9739.86 1.00
+1 haste +2.46 9740.49 1.34
+1 crit +1.48 9739.51 0.81
Finally I tried this with haste being over the haste cap, and crit being under the crit cap (405 haste/900 crit). Here haste sharply dimishes in value compared to spellpower and is even below the value of crit. So this is probably the general scenario for many boomkins (being over the haste cap, under the crit cap).
Over haste/Under crit soft caps
----------------------
Default DPS: 9990.97
Stat DPS gain DPS Normalized
+1 spellpower +1.87 9992.84 1.00
+1 haste +1.32 9992.29 0.71
+1 crit +1.51 9992.48 0.81
I hope this was helpful in deciding which stat might be a better choice given the current levels of gear.