I ride a 48cm with 700c wheels and a 170mm crank and of course get toe-overlap. Most of my falls so far have been due to locking up my toe against my front wheel while performing a slow long sharp turn. I also have to be careful during trackstands. Most of the time this isn't problem as I've come from a mountain biking background and early on learned how to ratchet to clear my pedals. The trick here is that I have to learn to ratchet for a different reason to clear an obstacle that is 90 degrees out of line from what I'm used to. Sometimes I forget and the wrong foot gets chocolate.