Well vampire and Ednor are really not that similar. I found them to be quite different experiences. Same with the two at Hershey. In fact storm runner seems to be one of the most unique coasters I've come across IMO. While I've been on quite a few launch coasters, not many have taken you through elements that high up.
Here's a thought. Personally I love mf and nitro but am not a big fan of behemoth in comparison. This new coaster seems more like mf to me than behemoth (in layout not trains). So are they really that similar? Could it not be argued that leviathan is going to offer a fairly substantial different experience? Behemoth seems to do the same thing over and over which is great if you like that, but I'm more a fan of twists, turns and speed. Leviathan seems to cater to that crowd.
Just my thoughts