well if the rating is lower there is no harm
on an aside note, the use of schottky diodes in free-wheel (or power electroincs) isnt best advised.
Schottky diodes are very fast/snappy. They have very bad reverse-recovery and thus will increase the turn-on losses on the switching FET/IGBT that will take the free-wheel current.
also since Schottky's are snappy, the FET/IGBT will tend to ring when it is switched on, thus causing the use of higher gate resistors to damp out such oscillations.
just an aside note....