My DD has both in that same length/drop. The joint on the 2012 Xeno is getting loose after a year plus of hitting. Only had the Onex a few months the joint seems to be made much better. Can't tell any difference in the bat other than that.
My DD had the same problem with her 2012 Xeno and it was declared illegal by an umpire during a tournament. I called Louisville Slugger and told them what happened and they replaced it with a 2013 Xeno no questions asked!
The rest of the story. DD had a 2011 that developed a rattle LS replaced it with a 2012 under warranty(same as JAD no questions ask). So we only had about 2 months of warranty on the 2012 bat.
I believe guero_gordo's dealer is correct if referring to the failures under warranty. In my experience the Xeno's won't last much longer than the warranty even for a contact hitter. I'm hoping the Onex will considering what we paid for it, but I'm not going to bet the farm on it.