My, I would not have thought this subject would stir such emotional responses!
I personally feel that sealed, aka Nev R Lube, bearings are a great boon to RVers. Those who do annual bearing & hub maintenance may have no need of them, but the majority of RVers are of the "drive 'em and forget 'em" mentality, so they routinely have bearing problems regardless. The ridiculous prices that RV dealers charge for routine maintenance is another inhibitor, as is the lengthy time to get service. So, a bearing designed sealed with "permanent lube" is going to be superior to one that requires annual lube but doesn't get it. I'll leave it for the gear heads here to worry about whether they are better or worse than the ones that receive annual care.