What helped me decide against the LN bearing last year (38k mile 04 3.2) was simple odds. Namely, the cost for Raby to do it, all in, was about $3500. That is 25% of the cost of a $14,000 engine replacement. I don't think I've ever seen anything approaching a 25% failure rate estimate. So yes, it's rolling the dice, but smart money says "Don't do it unless you at least need to be in there anyway for a clutch." And, the upside of doing the LN bearing is only peace of mind. The upside of replacing the engine is a 3.6!
Of course, if the $3500 is something a person can afford but the $14,000 would cause a real hardship, then the part of wisdom would be to buy the insurance for a $3500 premium.
(There are other shops who will do this job for less, and of course you could not do the clutch while in there and save some money as well, but I would have used Raby and I would have done the clutch, so that's why I used those figures.)