not sure you've seen SC on high if you think low and high look about the same. Especially when it comes to shaders. low looks just downright terrible even a big difference from low to medium, and this is even if only major setting changed was shaders.
i've seen it on low/med/high/ultra. on my desktop, i use ultra. on the 11", i use a mix of low and a few med ( I think just landscape on medium?), but basically it's low with shaders on. at the 11" size, the difference in quality is very minimal compared to the FPS you get. now, if the screen were bigger, the difference would be more obvious, but not at 11". I find that these are the best settings to play on, especially on multilayer.