it looks like the KSO has been withdrawn in favor of the KSO EVO?
Yes, the original KSO has been discontinued. I heard a rumor that they would re-release it in black only along with Classics, in 2016 to commemorate the anniversary of the original five finger sole. If you can't wait until 2016, then the KSO EVO is a laced version of the EL-X and has a very thin and flexible sole. Some actually prefer it over the original sole. As nowster mentioned, the Bikila is geared more as a running show with a slightly thicker sole. The Bikila EVO is a new version of the Bikila with a little more padding. If you are looking for less padding, then the original Bikila may be a good choice. If your form is good and your soles have been holding up fine on your other pair, just a fabric wear issue on the toes, then the KSO EVO would be a great choice. I really enjoy mine, however I am no runner.