.. the underlying message is, I suggest, don't trust your life to the whizz bang magenta line gadgets. They can be good (or bad) but he (she) who trusts them unthinkingly .. sooner or later is going to get a fright .. or worse.
Reflect upon how many code errors exist in the software on your home PC .. sure, the TSO'd things are better than that ... or, are they ?
.. and it doesn't really matter what you use as a check for reasonableness before pitching over (subject to the normal priority preferences) .. even a pre-thought out VOR/DME or NDB/DME fix is better than just sitting back and hoping that the box is telling you the truth.
.. or are some of us still in the early generation systems where "what's it doing now ?" was the catchcry ?