Can someone tell me the difference between the Nike Free Run 5.0+ and the Nike Free Trainer 5.0? Also: I'm currently running in the Nike Pegasus 30 and I'd like to run my races 5k up to half marathons in something lighter than the Pegasus but I don't want a traditional racing flat. Would the Nike Zoom Elite be a viable option? Thanks...male 64..145 lbs. pr for 5 miles 36:10 at age 62.