I forgot to add to the OP that I am running an AMD HD 5770 1Gb. OC'ed to 960/1380 (core/mem), so I cant use NVidia Inspector...

If you try forcing AA on ME3 (CCC, RadeonPro, other software here) on ANY setting, it has no effect (framerate or visual quality) whatsoever on a 1680*1050 resolution setting. (only the FXAA option works), UNLESS you use the tweak mentioned in the link in the OP or you lower your resolution.
Now as far as I've searched, I only found the tweak for a 1680*1050 resolution. But I believe that even running the game on a 1440*900 rez causes the bug above (strange, isn't it) because if I lower the resolution to 1360*1024 (one step lower) AA kicks in... I was wondering if the HEX tweak would work for me.
ME3 has very good FXAA.
Very good "FXAA" - Yes

Very good "AA" - HELL NO.... *nuff said*
