http://reynoldstechnology.biz/our_materials_853.php
E5 Alloy:
http://www.specialized.com/OA_MEDIA/pdf/Roadracebro.pdf
http://www.columbustubi.com/eng/3_2.htm

It seems that this is either a specific modulus of aluminum proprietary to columbus or a 5000 series aluminum.

As far as ride. I am prejudice. Steel feels better to me than aluminum, but if I had coin to drop on high end aluminum it might feel as good as steel. I think aluminum is too brittle (firm), steel is more elastic (softer).

My 853 rides great and would not hesitate to get another of the material.