Well, Tom, I saw (by accident) Mir cross the Moon on january 6th 2001 and it happens in about a second because both were quite high in the sky.
If ISS were very low (after zenith) above the horizon, it would seem to fly more slowly and then, it might indeed make a star occultation interesting.
But to predict an occultation of a specific star is extremely difficult! Even to be certain where position ourselves to see the station cross the moon is a challenge and not always successful.
The ISS's position must be exactly predicted and it changes all the time, because of atmospheric drag, even if it's very slight.

Raoul