Good morning,
For those who want to learn more about what's new in the Client Access Server role in Exchange Server 2013, the Exchange Team Blog has posted this :
Exchange 2013 Client Access Server Role - Exchange Team Blog - Site Home - TechNet Blogs
http://blogs.technet.com/b/exchange/archive/2013/01/25/exchange-2013-client-access-server-role.aspx
They mentioned the changes and why the change to RPC over HTTP has been introduced.
Very good detail and information.
Kindest regards,
João Ribeiro