Authentication methods in Outlook Anywhere

I see that part of the migration documentation suggests making the ClientAuthenticationMethod to NTLM and IISAuthenticationMethods to NTLM, Basic. in the current Exchange 2010 server settings, prior to accepting Exchange 2013 connections.

I currently have all clients set to use Basic authentication in the Exchange proxy settings. Will the clients be affected when I do this ? Does the proxy connection in Outlook use the IISAuthentic methods, so will not be affected or will the client update automatically ?