Well, I can't run perfect simulations at the moment. I also don't have my haste threshold chart handy. There is one posted to EJ by someone who put one together there but I can't access it. I need to know what haste threshold to set.
Anyways, I ran 3 simulations on my character with my gear at an average ilvl of 475.60:
1) Hit capped, Mastery > Haste > Crit, enchant = Power Torrent
Mastery Weight = 1.77, Haste Weight = 1.20, Crit Weight = 1.17
2) Not Hit capped, Mastery > Haste > Crit, enchant = Power Torrent
Mastery Weight = 1.71, Haste Weight = 1.17, Crit Weight = 1.17
3) Hit capped, Mastery > Haste > Crit, enchant = Windsong
Mastery Weight = 1.71, Haste Weight = 1.18, Crit Weight = 1.19
Looking at the BiS profile and reforges, not hit capping brings your DPS down. So it looks like at some point between my item level of 476 and the 503 BiS ilvl, hit capping takes a priority. Not hit capping right now, over 10000 iterations, results in a 850 DPS gain. To be honest, I feel this to be negligible as a miss at the wrong time (Haunt, one of your DoTs with SB:SS during execute) would cause a DPS loss. I don't like the volatile feel of not hit capping here, but play the way you want. I'd rather play knowing I'll hit every single time and do 800 less DPS, but that's just me. Also, Power Torrent appears to be better than Windsong until you get Jade Serpent enchant but most of the super high end raiders are using Windsong, so there may be something going on unknown to me. I know at one point that enchant was broken for DoT classes, but perhaps it is fixed now.
When looking at the T14 normal (ilvl 496) simulations, Affliction uses a hit cap and prioritizes Mastery > Haste > Crit.
I BELIEVE that the reason Ask Mr Robot and WoW Reforge put no value into Hit when it comes to maxing your character is that because if you were to push stats into Haste and Mastery and get lucky enough to never miss, of course your DPS will be higher for that parse. Over the long run, however, you will also have parses where you miss more than you estimate bringing your overall hit percentage to be what is shown in your character tab. These automatic reforging programs are designed to find the max DPS, but they are not finding it for overall parses. They are finding the statistical outsider and setting their weights based on that. This is not the best way to set your Warlock up for longterm, sustainable, consistent success. I will stand behind my research and work and back up this itemization priority:
2) Spell Power
3) Hit (until 15.00%/5100 rating)