Actually, running in 800x600 or 1024x768 without FSAA and with the 40.41 aniso settings at 1, I noticed texture swimming and popping in the distance, as well as tons of aliasing (noticable because it caused shimmer on a high contrast area of the maps). While turning on quincunx and 2x aniso at 800x600 resulted in practically the same performance as 1024x768 without them, but noticably improved the overall scene over either of the other two modes (jaggies mostly gone, swimming textures gone, etc.).
I'm gonna probably go back to the 30.82's and give those a try, just for comparison's sake (especially since K.I.L.E.R. reported they were smoother for him; I know he's got a GF3, but if the water's all that really uses shaders anyway, and all that the 40.41's supposedly optimized was the shaders..)