Okay guys, I think I may have something.
The ROEngine.ini OP is talking about. Make a backup (Rename it ROEngine2.ini or whatever), delete it. The thought occurred to me that I still couldnt disable AA ingame, only the ini tweak OP pointed out; even though I had thought they changed that in the second patch. I've seen this happen before in another game (whose name escapes me for some reason) where it was simply something was changed but the file wasnt updated properly.
By erasing that file (hence why I said make a backup) it creates a new, fresh file. I could disable AA ingame from the options menu. Checking again, there also seems to be a "Steam cloud" option that I don't remember being there prior to refreshing the file. I noticed my FPS (after setting everything back to where it was) was a bit better, from about 55-90 versus 40-65 or so.
Disabling Motion Blur also seems to be an improvement for a low cost BTW. It seems like I was getting a lower FPS when turning, turning off motion blur helped a bit.
Your mileage may vary and this may just be some mind trick, but it seems to have worked for me, still terribly optimized, but bit more bearable. Give it a whirl, hopefully it works for some of you guys as well.