Yeah, it's much harder to spot differences in high resolution anime because it's mostly solid lines and colors, as opposed to actual textures.

I think the main advantage of watching a high resolution version is that it drastically reduces artifacts and blocks. If I watch the 1080p version on my 22" monitor, it has to downscale it to 1680x945, which essentially removes all edge artifacts in the process. I get a perfectly smooth fullscreen image out of it.

With the SD version, the original resolution is less than 1/4 of my screen.