There's a lot of information in the Xtrain guide, more so than in more recent guides. So the question becomes "do you already have that information?" I think she goes over a lot of stuff. If you just use the rotations and cards, you don't need it. But there definitely is more to it than that. It is more informative, more like the STS guide with discussions of the philosophy behind the series, so if you want to use Xtrain a lot (and many do) I'd buy it.