If you mean Moving Beyond the Page, I can answer your questions (for our family, anyway).
We LOVE it. I have 4 of the age level sets, and have enjoyed every one. It's nice to either follow the entire rubric, or to get off on a tangent and delve into one aspect of the studies, as the kids' interests take us.
There is no additional outlay if you buy the whole shebang. We've also used RightStart math for years, and my youngest two are still using it now. However, around grade 4 we changed over to other math programs because a great deal of Right Start is done mentally, and there is no teaching how to write your process down. I know, not super important now, but being able to tell others how you're getting your answers does matter, especially in standardized testing.
It is *very* easy to follow, and I think expansion activities are kind of what the whole curriculum is about! :) Good luck!
love, p