In response to what willpell mentioned, the rate of lucidity varies from person to person. For example, most of my dreams (that I remember) are lucid, although I have never been able to successfully change anything. If anything, it makes my nightmares even more terrifying, as I know that logic can't help me, and that I can never entirely outrun the monster.
With that over with, I like these rules, simple and efficient. I'm assuming that for the most part spell duplication isn't all that necessary, as most effects can fall under 'cause significant chance to dream.'