Acer palmatum 'Beni Hime' is a beautiful highly desirable cultivar for the collector. It is a thin stem dwarf, slightly pendulous, with the smallest leaves of the species i believe. It is sensitive to fungal problems on the leaves if given constant moisture to them ( daily watering must not hit the leaves). I think it is best suited in the garden or in a pot in its natural form which would be a small canopy of drooping branches. As a bonsai, first you would have to accept the graft union, then the incredibly slow growth of thin weak very brittle stems. It may look incredibly beautiful in leaf, but will not be shown out of leaf. Maybe try it in a kusamono.