I tried to replace the Leap with a Mirra from Herman Miller. But I just couldn't adjust it to what was comfortable for me. And I didn't like the back. I'm not a fan of the webbing.
I gave it to my wife, and she loves it. But granted I upgraded her from a 80 dollar Office Depot chair :)
You should see if there are office supply stores near you that will let you demo the chairs. Not just for a few minutes but for at least a day.
A friend of mine just bought 15 Leap's in AZ. He was able to get a Leap, Mirra, and a couple of others to test out for a couple of days before making his decision. Might be something to look for in your area.