I'm not denying that the stuff works. But since it is a poison, that's exactly why it works. Your body wants to get rid of it.
But what really turned me off of Miralax was the number of people (like the unfortunate bride) who said that as long as they were taking it, and for some time after they had quit, they didn't dare get more than about three steps and ten seconds away from the bathroom. And these were people who said that, until Miralax, they'd never had a problem with incontinence.
Since wherever I happened to be, I'd have to climb into my wheelchair, make it to the bathroom, then transfer to the potty, I didn't want to have to deal with something that didn't give me sufficient advanced warning.