The M5 gimmick has great street potential. Flip a coin in the spectators hands, stop a watch, high impact and repeatable without setup. Spinning a borrowed ring with a Tarantula and making it land on their finger always kills.
That being said, a simple ambitious card routine can be amazing, the patter is the key. remember magic takes place in the mind of the audience, not in the simple mechanisms we use. If something is polished, visual and well-rehearsed it will serve you well but you need to get words in their ear to really elevate the experience.