Shortcode for duration of event?

Ok I ended up adding my own filter, here it is if anyone needs or need to add their own shortcodes that work in the EM Event scope:

#_EVENTDAYS returns “x day(s)”
#_EVENTSTARTDATE returns event_start_date

add_filter('em_event_output','mc_em_event_output',10,4);

function mc_em_event_output($event_string,$obj,$format,$target) {

	//Now let's check out the placeholders.
 	preg_match_all("/(#@?_?[A-Za-z0-9]+)({([^}]+)})?/", $event_string, $placeholders);
 	$replaces = array();
	foreach($placeholders[1] as $key => $result) {
		$match = true;
		$replace = '';
		$full_result = $placeholders[0][$key];
		switch( $result ){
			case '#_EVENTDAYS':
				// Return number of days
				if( $obj->event_start_date != $obj->event_end_date){
					$replace = floor(($obj->end - $obj->start)/(60*60*24)) + 1 . ' days';
				}else{
					$replace = 1 . ' day';
				}
				break;
			case '#_EVENTSTARTDATE':
				// Return event start date
                               $date_format = ( get_option('dbem_date_format') ) ? get_option('dbem_date_format'):get_option('date_format');
				if( $obj->event_start_date != $obj->event_end_date){
					$replace = date_i18n($date_format, $obj->start);
				}
				break;
			default:
				$replace = $full_result;
				break;
		}
		$replaces[$full_result] = apply_filters('em_event_output_placeholder', $replace, $this, $full_result, $target);
	}
	//sort out replacements so that during replacements shorter placeholders don't overwrite longer varieties.
	krsort($replaces);
	foreach($replaces as $full_result => $replacement){
		if( !in_array($full_result, array('#_NOTES','#_EVENTNOTES')) ){
			$event_string = str_replace($full_result, $replacement , $event_string );
		}else{
		    $new_placeholder = str_replace('#_', '__#', $full_result); //this will avoid repeated filters when locations/categories are parsed
		    $event_string = str_replace($full_result, $new_placeholder , $event_string );
			$desc_replace[$new_placeholder] = $replacement;
		}
	}		

	return $event_string;

}