Any non-technical reason you've got HBAO off? I'm running the same quality settings @ 1080p but with textures on high, HBAO on, and dynamic res disabled with a 970/4690k.
No, normally I think the effect really adds a lot, but I felt like Dishonored's lighting and texture design had enough depth without it, and it was the difference between dipping below 60 FPS and being above it regularly. Obviously I'd notice the difference in direct comparisons but it wasn't something where its absence actively bothered me while playing.