I see posts from a year ago from people who purchased the Magic Shine 900. One year down, do you find the Magic Shine reliable? Any problems?
I've had one for about a month and have used it without any issues. In general, the Nite Rider equipment is higher quality, and better engineered than MS.
One obvious difference is how slick the battery construction is. But if you want the most "light for the cost" then MS is currently the way to go.