I doubt you'll get valid data that can state SC shoes lasts longer than calf (or vice versa) because you can't control the variables of general wear. I think if we compare the materials, we should be more specific (and avoid cross-sectional approaches that look at numerous pictures of shoes), then we can at least better define "stronger" and "lasts longer." I think it's been discussed that when it comes to ripping, calf does have an advantage; however, when it comes to puncture and cuts, I think shell has the upper hands. There are a number of other ways to look at it... durability with abrasions, water resistance, etc.
At the end of the day SC is a smaller hide than calf and it will cost more to make shoes out if it. In addition, the current demand is high for this material so suppliers can charge more.
I like both, I wear both, and I buy both.