We do all our own theorycraft. We also don’t use stat weights at all - instead we created our own method for finding the best gear that is a data-driven approach based on simulation.
Picking legendary items is a very complicated problem that requires massive amounts of simulation data to solve correctly. We have been hard at work on a method to deal with it, and are nearing a solution that we can start posting up for all specs. It has taken a while because each spec requires millions of simulations to find the answer.
For right now, the best thing for you to do is create a custom gearing strategy for your character, based on the legendary items that you want to use. Then, lock in those legendary items and optimize around them. Hunters have a few options for legendary combos that work well. The trinket is generally much better for AoE fights than single target.