So, l'm a resto shaman MS, and have valued Int very high (using almost only +40 int gems etc.)
However, l know from WotLK atleast that haste was our most prio'd stat.
Now, for the "question" ... what haste rating/percentage do l want to hit? Will reforge crit/spirit/mastery into haste be a good thing, or shall l keep those anyway, or shall l simply make sure to reach a specific cap, and then go for crit/mastery/spirit?
The thing you have to understand is that haste will increase your throughput no matter what % you have. The amount of increase will vary of course.
However, with the changes to how haste interacts with Hots and Dots, certain thresholds of haste are increasingly important.
For example, (assuming you are using Wrath of Air or have 5% haste raid buff from a SP or other equivalent) you will need only 261 haste to gain an extra tick from your Riptide. Although you will need 916 to get an extra tick from Earthliving. Although that small amount of haste will not push your main heals down to a degree in which I myself would be comfortable. So its safe to say you will want more.
So the thresholds you really want to look at are 916, 2005, and 3966. There are thresholds in between for both HoTs but these are the most important ones in this tier of raiding. The actual soft cap on haste is 5489, but is impossible to hit and remain at a viable level of other stats. So it becomes all about your level of comfort with the cast speed of your healing spells. Your throughput will be effected either way, but its all about your playstyle.
As for reforging crit/spirit/mastery... Crit is a heck of a lot more important to resto shaman than it was in Wrath. They have removed a HUGE chunk of crit from us via the streamlining of our talents. The synergy amongst our talent specs with Improved Water Shield is gone. Thus gearing for crit is a necessity. Reforging out of crit and into haste may bring a small throughput increase during shorter fights and decrease your viability for longer ones.
Our mastery is extremely poor right now, but is being worked on in 4.06. Only time will tell if Mastery becomes a better stat. Until then, reforge this to Haste or Crit, depending on the availability.
Spirit is a necessity, however you do not necessarily need to go out of your way to reforge it onto gear unless you are using far too many pieces that were meant for DPS casters rather than the spirit based ones. There is no magic number for spirit. It is merely a number you will have to adjust based on your play style and encounter design. That being said, the new 4.06 version of mana tide will be completely based on your level of spirit so stacking spirit (as long as its not at the over expense of other required stats) will be a much better thing than it is now. Just remember that proc spirit from trinkets or Heartsong do not apply to Manatide in 4.06.
Thanks alot. I think I'll be forging gear / gemming so I reach 916 haste. After that I'll be forging into Crit. However, I "have" to keep my spirit quite low, 1468, since I'm draenei and elemental OS (sharing 15/17 gear with healing).