Sorry if this has been already discussed here, but as a sprint coach I'm trying to figure out if there is an advantage in the sprint events with the carbon plated spikes that have come out in recent years? Also is it different from 100m to the 400m distance. I work with very good, but not quite elite level sprinters (10.2 100m, 46.0 400m types), and am wondering if it is worth the extra expense to purchase them.