I think that both programs are solid and you will find those that absolutely love one over the other. I have RS and MUS. I really wanted RS to work (as I know it can and is solid) but I didn't give it the time necessary to do what was required, so we chose MUS. I don't think I'm lazy, just realistic. I do think that those that love it have given it the time necessary and that it just "jives" with them, their child(ren), and that is how most curriculum is chosen or loved.
We are continuing with MUS because my struggling student really needs simplicity. He craves all the fun stuff, dialogue, manipulatives, etc., but at the end of the day, it's all too much. In a previous program he was exposed to a variety of ideas in each lesson (he loved it) but not enough time was spent on one concept. My struggling student needs/needed that. My other two dc could probably use any program, and one does. But two of mine use the same to make it easier on me. If these two used different ones, they're would be fights over each other's supplies...why would I purposely do that to myself, LOL.