Brent, it is what I was taught in school, and from personal observation, the hubs packed full have little grease inside the actual bearing, and it is black, and smells burned, when I was talking to Storm Vulcan about replacing the spindle bearings on my crankshaft grinder I was cautioned about using too much grease ---that it would overheat.
So I googled timkin bearing lubrication --
http://www.timken.com/en-us/solution...n_Part1of3.pdf
Perhaps the bearing buddys allow grease movement, every thermal cycle the damaged grease is repleneshed with enough fresh grease to have acceptable life, and still I think the bearing life isn't the same, I don't know of many boat trailers that get hundreds of thousands of miles like a car, but I know of boat trailer owners that have had several wheel bearing failures on their trailer, but never on their car, Wal Mart has boat trailer bearing sets, but not car bearing sets --they deal in volume
My theroy on U-joint lube is that the grease is there to keep the leakage past the trans bearing in contact with the U-joint ---it fills the space, and helps seal the ball coupling. --I just keep filling the trans, pump a few strokes in the fitting for the ball socket seal