Bustanutley has said that the lower R&P are stronger than the higher ratio R&P, however he ha not said why. I can guess and say that it is due to the amount of steel and dia of gears in the pinion head.
Yep, well you wrote it backwards but you get it. The teeth are bigger on the ring gear, and the pinion is bigger. We have gone thru a bunch of lower gears. Our experience is that the higher gears hold up a lot better, 4.11 is as low as I would go.