Use SimCraft. This type of question is basically the whole point of it.
A question about DW State Weights and Reforging
At which point should reforging based on the iLvl 378 be switched to using the weights associated with iLvl 391? I've crested the 378 mark which is what I've based all my reforging against but it's unclear to me when I should alter my choices based on the 391 weights.
Is it only once I've hit iLvl 391 and above or is it after I've crested iLvl 378? I've been unable to determine this for some time and have also been unable to find information that gives guidance or a means for me to learn on my own. Thank you for your comment.