I prefer to make a custom site for mobile that is served up by the CMS without changing any urls or anything. All custom tailored for mobile devices. More to a mobile site than a design that fits in it, so just using a responsive design isn't gonna do anything.
Sure you can hide elements while on a mobile device via your responsive design, but you hide 2/3rds of your site and they still load that stuff, it slows down the users loading as not everyone is on Verizion LTE 24/7.
You gotta think about these things.
