I would like the ability to push an attribute or relationship down to a (specific) subclass or up to the superclass. Cut and paste would be a help, but it would be better to have the ability to say "push to subclass", and a list of sublasses pops up from which I select one. If there is only one, then it is automatically push to it.
Similarly, "push to superclass" would automatically push of only one, but provide a list if the heirarchy is deeper (from which I could select one).
This would avoid the "hunt and peck" effort that may be annoying with large models (I know I start to suffer from "cant see for looking" problems after a while