I was hinking about this today, and I decdided this.
4.7s in a single case is stronger than dual cases.
You see quite a few dual case setups brea the input shaft on the rear case. This I believe is because of the added torque from the crawl box. A single 4.7 case does not see this added torque. I wonder if this is why we only see 4.7 gear sets strip, and not the inputs exlpode like alot of 21 spline dual guys.
Just a thought I hadnt seen discussed yet on this topic