Lots of people want the Kevin Shields/MBV reverse reverb or early reflections sounds. Those aren't available in a stompbox other than the discontinued Yamaha Magic Stomp. An Eventide stompbox version would be fairly compelling.
http://www.google.com/search?client=safari&rls=en&q=kevin+shields+spx+90&ie=UTF-8&oe=UTF-8
