I tend to think that you get better subject coverage if you are more eclectic in your approach to curriculum choice. Throwing all your money into one company's curriculum limits your creativity and can hamper your child's learning style. I really like getting all the web site info from everyone!
Tempting, seeing that it's all developed for you. However, can you advance your child if they excel in an area? I think I'd prefer to be a bit more eclectic.