I'm already using it to quickly scope out accounts and have found that accounts I stopped supporting because they staked too little often still have a very high KE. I consider more than just this co-efficient though, such as what accounts they delegate to, and whether or not they have been in dire circumstances but are still publishing good content.
I like it. It's not the end-all-be-all, but should come in handy. Mine is 1.09.
Yes - it is a quick and dirty "red flag" system - but it is useful to raise that flag. And who knows, perhaps when more people dig deeper, they find out positive information about other accounts too.