I've got the [Vibram KSO][1] currently and it works great, especially for trail running. However, running on cement starts to hurt after a while.

![Vibram KSOs][2]

I'm thinking of getting a different kind, but there are several types that look like they could be candidates such as:

- the Bikila 

![enter image description here][3]

- the KSO Trek

![enter image description here][4]


Has anyone had any experience with these? How do I pick the right model?


  [1]: http://www.vibramfivefingers.com/products/Five-Fingers-KSO-Mens.htm
  [2]: https://i.sstatic.net/q71al.png
  [3]: https://i.sstatic.net/eU0BA.png
  [4]: https://i.sstatic.net/zeNS0.png