Using WP Alchemy output_filter

custom-spec.php

$custom_metabox = new WPAlchemy_MetaBox(array
(
	'id' => '_custom_meta',
	'title' => 'My Custom Meta',
	'template' => get_stylesheet_directory() . '/custom/meta.php',
	'output_filter' => 'my_output_filter',
));

function my_output_filter ( $post_id )
{
	$page_template_file = get_post_meta( $post_id, '_wp_page_template', true );

	$post_template_file = get_post_meta( $post_id, '_wp_post_template', true );

	if ( 'post-template.php' == $post_template_file || 'page-template.php' == $page_template_file )
	{
		return true;
	}

	return false;
}