Yeah, so I tried it in CSS and my diagnosis is that it eats frames worse than HDR.
When I turn everything on max (6x AA, 16x AF, etc) and HDR and Adaptive AA at 1280x1024 i get around 30-40 frames in an empty map with 3 bots (i tried on nuke). As soon as I turn off Adaptive AA I get frames up to 80 but not very stable. Further, when I turn off HDR I get almost no framerate loss, but I know it will decrease with more ppl in real servers.