I'd think this would be used mostly by power users not by the average monk. Thus, it would not add too many database hits. OTOH, you could argue that for that reason it shouldn't be added as a feature....

Also, I have no idea how the PM engine works, but are nodes cached as they are displayed? If they are, then the hits would be minimal, because by definition the page has already been displayed. (If they aren't cached, why not?)