I did some reading on the Iyo and (at least on the woodworker's forum) has been noted to dish easily. 330mate.com gives it a 3 of 5 which would make it similar to the Aoto (maybe a little harder).

FWIW, So on Japan Tool slots the Aoto as a stone to use between 2K and 6-8K. It seems his recommendation is to use a 1000 (synthetic)> 2000 (synthetic) > Aoto > natural medium finishing stone > natural finishing stone.