I've had an X9 on for about 9 months and just busted my derailer hanger. I thaught that the mech was ok But no. I hit in on a lump of wood riding in a pine forest. The mech is twisted and busted of the lugg which holds the bottom arm sprin tension. In it's twisted state I ahve been able to keep it working quite well.
The moral is that if the hanger broke the derailer should be OK, (maybe), if I had been able to get parts it could be fixed properly but no chance there. replacement only. At least replacement isnt going to send me broke.
Untill I hit it, it has worked perfectly needing adjustment only in the first week of use.