I was looking for somethings like that too, i was thinking to do it using a external client .
From my point of view, you could do even more.
For example, you could have the impact of every spell on your DPS/HPS/dmgTaken
You could have the stats weight for every specs on DPS/HPS/dmgTaken.
I'm thinks about that because of machine learning, actually simscraft, amr, datasheet are using a "simulation" of the game. It need to know how it's works for every spell, bosses, rotation etc... So i wonder, why not using datamining / machine learning to provide some tools : best rotation, best stats, best item. There is no need of having a big data like wowhead. Only need to mesure 1 logs every/hour for one spec, run it inside the machine learning.
The default of this idear is, if the community are doing it wrong. For exemple going for crit when mastery is better. This client will never know it.
I will work on that, but i only know Java, so it could take times.