I wonder if it would be good for the FAQ to include a link to this page from the Agatine Eyelet: Obsessed With Alden that discusses the performance of various Alden soles in the rain: http://theagatineeyelet.wordpress.com/2010/10/07/rain/.
I found this there:
"Plantation Crepe – Great traction and rain resistance, but the leather tip can get funky and peel back when it gets soaked."
The fact is leather soles are leather. At the Wolverine blog they suggest using waterproofing on the leather soles of their 1000 Mile boot. I have done this in the past and it does help in preventing the leather from soaking up water.