Post processing AA works great at relatively high resolutions, in fact it's basically impossible to tell the difference in IQ between x2/x4 MSAA and a good postprocessing algorithm like SMAA T2x at 3840×2160 (while the performance gap is absolutely brutal).
I'd stick to postprocessing only for anything over 1080p.
Gopher mentioned it helped him in his testing phase, and I also chose to use it earlier to smooth edges. My recommendation to save FPS is to reduce Effects Quality to Low settings; provides more natural appearing FX with less shine. This not only lessened the distractive FX, but boosted FPS and aided immersion for me.
The problem with the effects setting is that while abilities might look better at lower settings other things like fire end up looking disgusting.
I've tinkering a bit and so far the best results (imo) are everything maxed with post processing at the lowest to remove motion blur, I've been thinking about using SweetFX to desaturate the game a bit but I haven't tried it yet.