I don't run often but I have been making an effort to get myself into the habit of doing it more.  I have run on shox, zig techs, asics etc.  I loved my shox until I put on zigs, I absolutely love my zigs however they don't function on anything but relatively level flat ground.  I took these out for a test run as part of a Cross-fit workout.  They are very light, I love that aspect, you know they are there but they don't feel heavy at all.  The feel of the landing is different and it took me a few minutes to adjust my stride.  The arch support in the sole is fantastic and the flexibility gives you a rough feel of the terrain you are running on. I very much enjoyed my first use and am looking forward to many more.  I typically wear a size 10.5 but found a 10 fit me better on these.