It's on our wishlist and we have actually tried a generic implementation with support for all dynamic properties so its not a technical problem, the main issue is how to present the GUI for the editor with all these options available for inheritage. My suggestion right now if you only need this feature for a boolean value and don't want the double properties is to actually develop a tristate property that you can use instead of boolean, for example by inheriting from PropertyNumber and adding a dropdown with values (Inherit), Activate and Deactive or something similar. It should be a fairly simple hack, you got the source for PropertyWeekDay in the SDK under source/EPiServer/SpecializedProperties that present a dropdown and stores it as a number.