Allowing the user to clone an attribute set and continuously update the underlying list of values for each attribute, but do not copy the actual set value for an attribute when pasted...leave it blank. This fixes one of the biggest shortcomings of mind maps in my opinion.
Example: Create an attribute set called "Address". Add attributes like Type, City, State. Enter a value for each of the 3 attributes. Now clone this attribute set and paste it. The cloned block shows the same attributes, but the 3 attributes do not show a current value. You click on the pulldown and you can see the values from the original and other clones. You can enter a new value or choose from the list. As you add new values, these become available to the other clones.