I haven't said that haste isn't the way to go, or that it isn't a dps increase, I am however saying that your sample size are too small to base an opinion on due to the RNG nature of the RPPM system. Which kinda gets proven when you can get a different amount of thunderhawks on a pull-per-pull bais.
But yes, haste should be the way to go when you have any RPPM items because it will, on average, be more procs than with a mastery setup.