How old is your FireCat. If it is 2008 or later and has Cat cams then the Onza will draw and feel just about the same. The Nitro cams are nothing more than a slightly tweaked version of the Cat cams.
If you're truely interested I have a new Onza for sale listed in the classifieds on the Martin TechForum. You won't see a better price and I live just west of you near Harrisburg.