I normally play destruction going full on mastery , crit then haste. I really love playing destruction but there are fights where im just thinking to myself " Why am i not playing afflic..." Proctectors , Thok , IG etc etc
So in terms of stat weights ( from what i've read here and other sources ) im thinking i should go 9978 haste , mastery then crit.
Keeping in mind destruction is my MS so i don't want to sac too much in favor of afflic , so im not really sure if i should go with the stats above or just keep with existing reforges and just equip a few haste items such as Garrosh's trinket.
This has kinda been asked elsewhere so in the future I might encourage more use of the search function. However if you mainspec destro your first priority is max mastery. After that haste and crit are basically interchangeable. However if you offspec aff you want to go mastery > haste > crit in your itemization. Don't stress too much over breakpoints. There are some breakpoints such as 10124 in destro for immolate but its not worth losing mastery over. Aff works just fine as long as you focus on haste/mastery to the expense of crit.
Haste and crit are pretty equal for destro actually. You will probably even notice a small dps gain on many fights if you go haste > crit. And of course haste is far better for affli as well.
Reforge all hit/crit in to mastery/haste. If you're close to an affli haste breakpoint (like the 9778 one), it can be worth sacrificing some mastery to get it. But don't bother if you're not very close. I wouldn't ever bother with any destro breakpoints.
And if you're ever short on hit, use expertise/mastery gems in red slots instead of reforging for it as much as possible.
When using expertise/mastery gems remember to compare the value for the stat you are getting by dropping hit (or not forging into hit). This becomes a no brainer at higher ilvls for destro where all 3x stats are 2x int even but at more moderate ilvls its still is worth comparing.
If you have access to a reforge mount in your raid, I would make it so that you can be at good affliction haste points on your gear, then reforge haste into crit on the fights you go destro. Too much haste causes you to be gcd capped on incinerate during backdraft procs (not sure what the exact number is, but if you have a lot of haste on your gear anyways, you will see it happen)
I'm in a completely destro biased reforge stacking mast > crit >>> haste and I never see any difference in numbers when I switch to aff from when I was mast > haste >>> crit. Sometimes I end up seeing a dps increase even from it.
Bindings kind of throws everything off and gives crit a lot more value than people give it credit for. Pretty much as long as you're stacking mastery as heavy as you possibly can there is no bad reforge for either spec.