I bought these to wear with my Vibram Five Finger shoes on colder days. I have not raced with them, but I am guessing it will solve my problem with my timing chips rubbing on my ankle. They are too hot for me to wear inside. I do really love being able to wear socks with the VFF's and these are perfect.
I have been using the Injinjis for 3 years now, mostly for long runs (10 km and above). Since I started using them I have had zero problems with my feet. No blisters! The longest run I had was 30 km and my feet were doing great. No chafing of toes. And I think my running form has improved.