Most people see the pros of responsive design being one codebase with a variable visual layer via CSS media queries, and the pros of an adaptive, mobile specific site being able to use a mobile framework from the start allowing for some device-specific functionality and overall just being a more lean solution.
BUT... If I'm designing a site and have the key components of a responsive design (flexible grids/images, media queries with break points), is there any reason to not have a case when I hit a mobile-friendly resolution where I completely change the UI and even then use a mobile framework like mobify.js? Understanding the implications of loading multiple frameworks for all users, couldn't I just hide the full mobile functionality the same way I'd hide a div using CSS?
Is there a solid reason for or against this solution?