It actually sounds more like you are proving that Str/Wis does less damge then Str/Int since you weren't pulling aggro as much, and are spending more time using all your deaggros.
I would chalk your aggro problems up to MT group hate and getting used to the aggro change. I agree that I'm pulling aggro more then before, but there are ways to counter that without having to spec to a lesser AA setup.
Does you guild use a Coercer, Dirge & Swashy in the MT group? If not give that a try and see how your aggro it. If you already do, is the coercer slacking? The new aggro changes changed them from a hate buff to a partial xfer, so maybe they are used to sitting back a little and working their control effects and need to switch to a more offensive nuking style.
Do you use Grandmaster's ignorant bliss? Did you spec your assassin AA's to increase the effects of the Ignorant bliss? Maybe try adding a propogation specced warlock to your group to proc it more?
There are a bunch of things I would try first to lower my aggro before going to a Wis AA spec, but if it works for you then go for it. It has some nice effects (smokebomb) that are certainly raid friendly, but I prefer my Int.