Quote from Scyfon
Hm...I don't think so
It doesn't "feel" the same. In S.A there was a main goal - to become #1, in KWMS there isn't a particular main goal. At first I thought that it was gonna be the same (they end up together at the end), but then they hooked up not too long after the first chapter :\
The main love interests are different as well. Kei was always teasing Hikari for being #2 and hardly showed any signs of how he felt for her and even when he did (when he was saving her etc.) he teased her afterwords to make her doubt his true feelings.
Usui is open about his feelings for Misaki. It was never hidden. He teases her by showing his affection for her (which annoyed her at first), and does nothing that sorta demeans her like Kei to Hikari.
Now, before someone else mentions the "onigiri similarity" again, I must say, IT'S A GODDAMN CLICHÉ! It is not unique to either S.A or KWMS. Many other manga with similar female characters have done it before -_-
There may be some similarities, but not too much.
I also was going to say that the "feel" or "rhythm" of both are not similar. Even if the characters and the plot have some (in my opinion) small similarities, they have way more differences. I think there's no way that the endings can be the same so that's way I continue reading KWMS.