W3TC and Browser Redirection for IE8 in WP3.5

Hi Everyone.

First off I want to thank the developers for creating W3TC, its freeking awesome and does so many things that I consider to be magic that it is truly a gift. Thank you for getting all my sites load times to under 1 second and better!

My problem is that there are still people that use IE 8 any 7 in the world. I know I am not alone here. Unfortunately these people are also paying customer and their customers…

The crux of my problem is that we had a really sweet responsive theme developed and it is like butter and the leads are piling up because of it, as long as users are not using IE 8 and 7. If they are on those browsers then I have to redirct them to an old version of the site using this code:

<?php
/*
Plugin Name: Serve Default to IE6
Plugin URI: https://www.nathanrice.net/blog/serve-ie6-visitors-the-default-wordpress-theme
Description: This plugin will serve the default theme to any visitors using IE6.
Author: Nathan Rice
Author URI: https://www.nathanrice.net/
Version: 1.0
*/

add_filter('template', 'serve_default_to_iesix');
add_filter('option_template', 'serve_default_to_iesix');
add_filter('option_stylesheet', 'serve_default_to_iesix');
function serve_default_to_iesix($theme) {
	if(strpos($_SERVER['HTTP_USER_AGENT'], 'MSIE 6') !== false)
		$theme = 'default';

	return $theme;
}
?>

This solution while not ideal was working until I installed W3TC with minify settings on. Once I turned minify off the redirect worked. Until I upgraded to WP3.5 last night.

Now I have to turn off Page Cache and the redirect works, but not for all sites.
It works on dmcantor.com
but not for cantorfraudlawyers.com

Any help is greatly appreciated.

https://www.ads-software.com/extend/plugins/w3-total-cache/