I have been using RightStart for several weeks now and we love it. I am teaching a 5yr old starting at the beginning and a 9 yr old (starting in the middle) using this program. We have used MUS and Singapore in the past and I think that RS is much more effective in teaching concepts because it is activity/game based. I wished I would have started this from the very beginning because it is difficult to start after your child has learned a certain way from other programs. They do offer “Transition” lessons to help your child ease into the program but it moved to slow so I am combining several lessons together to go at a faster pace. Singapore is so inexpensive that you could supplement those workbooks for extra practice if you wanted but it is certainly not necessary. When I talked to a representative for RS she said that she had a lot of moms that had come from using Singapore that said it was a relief because RS offered more than one way of explaining concepts.
Hope that helps. 🙂