So, as you can tell by my armory (if you looked), I'm DW Frost. I've read all the guides, tried to make sense of the gobbledegook on EJ, and all that fun stuff. I ran myself through SimC using my current gear (yes, I know the gloves aren't reforged, I just got them this afternoon) to get my current stat weights, and with what I got, Mastery ended up being slightly higher valued than Haste. Plugging these weights into Ask Mr. Robot, it told me to replace my orange gems with STR/Mastery and to reforge some of my haste into Mastery. The net change worked out to be around 5.60% Haste lost to 5.90% Mastery gained.
For clarification, I had SimC set up to run for 10k iterations, Patchwerk, single target, Player Skill: Good (this is being generous :P), all raid buffs, scaling all relevant stats (STR, Haste, Hit, Exp, Mast, Crit, AP). I'm having trouble believing that would be a dps increase. If I went ahead with this reforge/regem, I'd be sitting at about 45% haste and 33% Mastery. Any thoughts/suggestions?
It would be hard to really tell without running two dps tests. I would personally recomend using the dummies, but realize in some movement intensive fights the actual dps *should* be lower. Anyway though, you seem to be really solid gear/enchant wise, so i believe such changes will be minimal at best.
What is the problem? Mastery > Haste is correct for DW. Haste will sometimes outweigh slightly on single target but since the majority of DW's damage output is from Frost sources, Mastery is much stronger than it is for 2H.