I don't get it. Probably the biggest issue with Warfarin is that you have to watch diet and other things that may impact your INR, and you need to get your INR tested to confirm that your INR is in range. As others have noted, it's easy to reverse the anticoagulant effects of Warfarin. FWIW, warfarin costs just pennies a day. Testing, if you do it at home, weekly, is about $5 for the strips, if you already own your monitor.
Until there's an alternative that can be easily reversed and that is proven to work effectively with mechanical valves (and not cost a knee and an elbow), personally, I'll stick with Warfarin. At least I know how it works and my insurance can afford it.
I would not take Xarelto off label, even if a doctor thinks (yes THINKS) that something else may work - the risks would be too high, and the doctor wouldn't look all that good if his advice caused injury to the patient. .