I ran the aluminum cases for 12-14 years in my Dart Sport running mid-low 11's @ around 3,500 lbs footbraking between 1.47 and 1.53 60'.. I think it helps gear life a bit, but the ring & pinion has always been the weak point and I broke one or two and caught 1-2 in time. They were run a lot. That 11 lbs does make an obvious difference when lifting it into place! Used a steel billet yoke too.

Less ratio often means less, but bigger teeth, which are stronger.