Normally I just use the default stat weights when doing a best in bags. I noticed that when I customize and experiment with the sliders, I can actually get to more than a 20% DPS increase. Is this something that I should be doing or is it best to just stick with the defaults?
You could try a simulation to see if the score increase is actually that much higher. Or post a snapshot and we can look. Hard to say if it is a real gain or a weird score due to the customization.
Once you use the stat customization options, the “percent increase” becomes pretty relative… think of it more as a score of how “close” you are to your specified stat distribution.
Once you tweak the customization options, it’s not really a DPS prediction anymore – you can’t compare it to e.g. the predicted gain when you haven’t customized it. You also can’t really compare it to e.g. the predicted gain if you slide it all the way to Haste vs. the predicted gain if you slide it all the way to Versatility.
Put another way: say your gear has all Haste on it and almost no Versatility, and you decide to customize your stat distribution to get as much Versatility as possible and as little Haste as possible. The “score” is going to show a very large gain when we reconfigure your stats, because your current gear is very far from your specified target.
That doesn’t mean a high vers, low haste build will necessarily be better than any other build… it just means that your current gear is not great if that is your goal.