I see the benefit but it is very hard material. Consider the curb weight and traction limitations when selecting a diff size. Most go for excess capacity/weight/parasitic loss. Numerically higher ratios are weaker for a given diff size (thinner teeth) so that is another consideration.
There are surface compression processes (similar to shot peening) that reduce the friction but pricey for a few hp.
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Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS
viewtopic.php?f=5&t=13225&p=134742Simple Spring select
viewtopic.php?f=5&t=11815LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12