If Rawr works for your spec, it's going to give you better answers than Reforgenator or Ask Mr. Robot, since it develops its 'stat weights' by comparing the numbers between your current setup vs. the proposed one.

Reforgenator, by default (or at least last time I looked) had an uncomfortable love affair with mastery, too. It also has serious issues with expertise, since that's the only stat in the game where rating-to-stat is a discontinuous function.

Ask Mr. Robot apparently assumes (from what I've gathered in-thread from the folks behind it) that your stat weights in best-in-slot are going to be the same as whatever crap gear you're currently wearing. The only real advantage to that is that a best-in-slot set can be defined, so you have fewer arguments about the default. Doesn't make it any less arbitrary, though.

Ideally, for Reforgenator and Ask Mr. Robot you should be using something else to generate your stat weights. And each time you upgrade, generate them again. And generally do enough research so that you can find out if there's non-obvious plateaus to keep an eye out for (haste is a frequent offender here, on top of actual caps (soft and hard) for hit and expertise.)