i've used both. i've used OM kindy and secular sonlight p3/p4 and p4/5 with guide books and i've used OM 6th grade with secular sonlight reading list from their 1 year world history overveiw but no guide book.
i really like it and i think they complement each other pretty well. I really found i like them although do get the sonlight books if you can ahead of time to check them out before you buy.
SO far i've not felt like it was too much. OM is my spine and although we read the sonlight books we do their guide books activites only if we feel like it. Now i've not tried adding in their whole science or a math program along with OM but I don't think it would of been a problem to do so. I would just pick one or the other as your main curriculum and then use the other one to supplment.
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