Room modes removed, both speakers look pretty close. If you consider the Klipsch tower full range, then you would have to consider the Tempest full range too.
As mentioned in the emails before you ordered, I thought they would be fairly similar......IF you didn't need any more volume out of your set up. The benefit (if you don't need more volume) would mostly be a larger sweet spot and great dynamics with the Fusion-12. Now if you needed more volume, then it would overtake the Klipsch as you pumped more power to them.
I don't recall how much power you're using, but the Tempest will really shine and stand out when you start putting more wattage to both speakers. As the Klipsch start to show stress, the Tempest will be asking for much more.
When people are curious which speaker to buy, I ask how big the room is, what they're using now, and if they're looking for a decent step up in volume and dynamics. If they don't need more volume than their current speakers, I'll usually recommend the Fusion-8 or Fusion-10. But if they're at all worried about that not being enough, they often go with the Fusion-12. The problem is that many people don't realize just how loud these speakers can play if they feed them some extra power.
Amo76, if you're still wondering if these can be run full range, put in some some good strong music and turn them up until you can feel it beating on your chest.
If your receiver doesn't put out enough power to do that, or you hear your receiver struggle, you can try a more powerful amp.
Also, you should experiment with turning the speakers into the room even more.