What shutter speeds did you use? A lot of people think the benefit is with 'long' exposures, but not really. Fast and slow shutter speeds really don't benefit from MLU, whereas between around 1/20 and 0.5 s you should see a benefit.
MLU + EFC is even better. See: http://krebsmicro.com/Canon_EFSC/index.html for examples.
Good point, ive just checked and they were all luckily manually set, at 1/4 !