For durability:
What has me most impressive is that this leather coat really holds. I already have my second pair of these luxury Birkis. My first pair should probably get new soles * sometime soon. Nevertheless, the leather lining is still in excellent condition. [The wants what's hot ;-) at my feet] Therefore 5 stars. The extra cost is worth it, in my view.
*) One more additional remark: you can send in his shoes directly to Birkenstock and get a fair price new original soles. Worth at least if you can send a contribution of several save and Porto.