I later realized that the hash generated for both versions of a file (debug=0 and 
debug=1) is the same, when shouldn't. So:

public function getHash() {
    if ( isset($_GET['debug']) && (int)$_GET['debug'] ) $debug = 1;
    return hash('md5', implode('', $this->files). $debug);
}

Cheers,
Victor

With the SVN version this will be easy. Have the user code listen for the GET var and
set all the minifiers to use an identity function. Something like:

function identity($content, $options) { return $content; }

$minOptions = array();
if (isset($_GET['debug'])) {
    $minOptions['minifiers'] = array(
        'text/css' => 'identity'
        ,'application/x-javascript' => 'identity'
        ,'text/html' => 'identity'
    )
}

Minify::serve(
    'ControllerName'
    ,array( /* controller options */ )
    ,$minOptions
);

The controller and Minify options have been combined, so now this would be slightly
different:

$options = array();
if (isset($_GET['debug'])) {
    $options['minifiers'] = array(
        'text/css' => 'identity'
        ,'application/x-javascript' => 'identity'
        ,'text/html' => 'identity'
    )
}
Minify::serve('ControllerName', $options);

This was added in 2.1.0, can be enabled in /min/config.php