The Op wrote " We would appreciate it if anyone out there has experienced a bad outcome from using ULSD in southern Baja, will you please let us know?"
So far, and after following this question in one form another for years, the answer seems to be that NO ONE has ever posted a comment on using the diesel in Mexico that has caused a problem mechanically or warranty wise. I do remember one person claiming his truck was doing a regen burn more often than he recalled. But this was one person and I doubt it would fit in any scientific equation.
if there were any real problems, you can bet it would be all over the forums. And it is not, even after all these years.