Good question. The sub pixel resolution is less than striped RGB. Striped RGB will therefore potentially achieve greater sharpness for the same (full) pixel count, in horizontal direction. For instance you want to make a white dot at the intersection of all 4 pixels with a diameter of one (full) pixel. For the RGB you will have 6 pixels in horizontal direction you can use (+ more on each side if needed). For S-stripe you only have two. Hence, the accuracy you can achieve is less. In vertical direction it will be a bit more for S-stripe than RGB.

But, and this is the clue to pentile as well. At each sub pixel intersection you have all three colours available for S-stripe and pentile, but only two for RGB. RGB stripe only has high accuracy when going into the pixel, but low when going out. Pentile has high accuracy when going out, but lower (in saturated blue or red) when going into the pixel. S-stripe has high accuracy all over.

Clearly the s-stripe is superior to RGB stripe and pentile. I suspect we will see lots of S-stripe amoled in the future, also with relatively low pixel count.