So I roll a demo lock and I keep reading that Haste>SP>Crit.
Im not at the GCD yet, but I wonder when I start seeing diminishing returns on haste.
Currently my un-buffed stats are:
sp:3141
Crit:39.07%
Haste:1063
Im thinking that I should start moving some of my 12sp 12haste gems to 23 sp. Also I have the heroic Scourge Baton that Im thinking of using instead of the Heroic Lightbane Focus.
Well, you read wrong. It's SP > Spirit > Haste > Crit. SP is worth two to three times as much as Haste and Spirit is generally worth about 150% as much. That said, Haste doesn't really have a cap worth speaking of for Demo.The only things you can haste cap on as Demo are Immolate, Immolation, Life Tap and Curse of Doom. You won't cap on Shadow Bolt, Incinerate, or Soul Fire in any attainable gear, so don't worry about it.
You should basically be gemming entirely +23 SP, with SP/Haste only if you can get 7 or more SP from a socket bonus and SP/Spirit if you can get 5 or more SP. SP is so much better than every other stat as Demo that it's silly. So again: SP > Spirit > Haste > Crit.
At some point during 3.3.0 (not 3.3.3) there was a point where haste > sp. This is no longer the case - SP is king for all specs at all times and you will never reach the gear level where this changes with current 3.3.3 mechanics.