I do agree with you, when say that the approach is not right if we want to have a exact BIS equipment.
Model is non-linear. If it was, scale factor would always be the same and model would be
But we saw that SF change depending the gear you have. So SF_haste would be a function like SF_haste(haste,crit,SP,...).
Scale factors are fined for a one by one equipment switch but not to find a combinaison of gears.
However, I think that simcraft has done most of the reverse engineering to get a model close enough to the wow reality.
Is there any mathematical representation of that model ?
So why not just trying every combination but use the simcraft result instead of using scale factors ?
For the programme, maybe could you how us a sorted list of the best in slot gearset instead of the very best that nobody won't ever see ^^.