coach d wrote:
Some so-called experts have claimed for years that racing in flats/spikes does not confer advantage if the pace is slower than 6 min. I'm not sure if there is evidence to back that up, but I am sure that racing in flats with a lower heel lift places additional stress on particularly the calves. You want to do a fair amount of training in flats if you are going to race 13.1 miles in them, and by the time you do that you should have a pretty good idea of the times you can run in them.
I agree with the previous posts regarding the dangers of using a lower heel-drop shoe suddenly, without a transition period
If the heel-drop consideration is a major one for you, then you might want to give the Brooks racers a whirl (ST5 for stability, T series for speed). They have a higher heel drop than most other racers; 12mm for ST5, 11mm for T series (currently T7, with the T8 reportedly due for release in Feb).