if its any help, i own/run a garage. very rarely see the x-trail for breakdowns. we do, however, service a fair few.
the only thing, of the top of my head, that gives trouble is the ABS system. have changed a good few sensors. they are not cheap. round 200 bucks iirc.
and they need a good quality oil in them!
as an aside/coincidence, conversation in pub tonight, pal asked me to recommend a 4x4. first thing that came to mind was x-trail. strikes me as reliable.