Hey everyone, I'm one of the people from Ask Mr. Robot and wanted to clarify a few things.
1. Mastery > Haste. We only found a 0.1% DPS increase by swapping Haste and Mastery. Demonology is a spec that lends itself well to heavy AoE burns or single-target burns. And those situations favor Mastery more significantly since you almost always do them in demon form. That's why we chose Mastery over Haste in our default stat weights.
2. I can't speak for other sites, but we research all of our own stat weights, as well as work with a lot of the top theorycrafters. No regurgitation from us

We actually wrote a program that interfaces with SimC to sim through a lot of different gear options. As Sifuedition said, a lot of weights that people quote are based of THE BiS list, which you normally don't have. We actually take that into account, getting weights that work across most high-end gear levels, knowing you won't have BiS. And when you want to change the weights on your own, you can do that in AMR
3. We have an option that lets you export your gear to SimC. You can then sim your gear and put new stat weights into AMR if you want to be advanced

It's a very flexible tool.
4. Our BiS sets are actually dynamic - all based on the stat weights, selected options, as well as racials, professions, etc. Any time you change one of those options, Mr. Robot recalculates your BiS list, as well as the rankings for all of the other gear in the lists.
That all being said, if anything thinks we aren't handling your characters right. Tell me your character's name and realm and I can dig into it.
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