I've got a pile of spare saddles in my garage. I keep even the ones I don't like. At first I did this because I'm a pack rat, but as a side-effect I've discovered that at least one saddle that I didn't like on one bike I did on another.
The riding position between the 7.5fx and the Fantom Cross is a bit different, so you might not like the saddle as well on the Fantom Cross, but it's definitely worth trying. In general, I think wider saddles work better for more upright positions, but everybody's got some minimum width below which nothing will be good.