I think Alpha rolls can be extremely beneficial in correcting an aggressive dog when done correctly. My pit/corgi mix (Buddy) likes to try to attack one of our other large dogs. All I have to do is look at him and he rolls over, even with the other dog standing there. The other dog, Fonzi gets hyper. I'd never think about rolling him for his hyper behavior. That just tells me he needs to go for a walk.

Though I would like to add that even rolling Buddy would prove dangerous by anyone else (my sister tried it and he growled at her until I gave him 'the look'). I have spent many hours with this dog, and do this because it is the most efficient and easy way to get him out of his aggression mode. Most of the time I use positive reinforcement to train my dogs. Buddy came with some past issues I needed to work through, and it helps me maintain control and safety in my pack.