Split post title for styling

Will the format always be as you described? I.e. can we use ‘x’ as a delimiter to split your title? If so something like this would work:

add_filter( 'the_title', 'wp123_custom_title_format', 10, 2 );
function wp123_custom_title_format( $title ) {

    // if you only want to modify certain posts you can do a check here

    // use 'x' as your delimiter
    $pieces = explode( "x", $title, 2 );
    if ( 2 == count( $pieces ) {
        $title="<span class="boldtext">" . $pieces[0] . ' x </span>';
        $title .= '<span class="normaltext">' . $pieces[1] . '</span>';
    }

    return $title;

}