Anyway, back to Aldens.
Request some material samples and conduct your own lab research if you're demanding definitive evaluation. Otherwise, make a decision based upon the best information at hand like a rational person. This is tantamount to the horsehide vs. steerhide vs. calfskin motorcycle jacket debates I've seen; there is no end-all answer because of all the variables.
Is shell better than calf? Better in what way?
Is a drag radial better than a low-friction eco tyre? On a drag car, sure. On a Prius, no.
Break down your q a little more...
Which one do you think is more likely to dry-rot?
Which one will retain natural oils longer?
Which one has better weather resistance?
Which one has better pH stability and chemical resistance?
Which one has better abrasion resistance?
What is the ideal Young's modulus and which material comes closest?
Which has better shear strength?
Tensile is probably the least important lab relevant metric.
With the appropriate care for each material, a lot of factors are irrelevant as they will both last plenty long.
You can find an 80's Jaguar on the road today, just like you can an 80's Civic.
So the real question to me seems to be, which one required more upkeep? Ceteris paribus, given equal neglect, I believe shell would hold up much better. If you're going to take great care of your shoes, then shell would seem to have negligible benefit to cost for you from a functional perspective (aesthetics aside).
I'll just wander away now so as to not ruin the Alden thread, lol... :D