I have no experience of Ravenstone, but I don't agree with Ioana's view regarding Alderbrook's lack of academic rigour; having read Jo's post on Ravenstone it actually looks like the two schools are very similar in the way they nurture and challenge all children.
I have a scientific background, and I am impressed with the way they develop the children's problem solving skills and how they teach them to "think scientifically". Children are assessed and monitored continuously, but without much stress, and I have always been pleased with how all teachers knew my children and what worked best with each one of them; in each activity there are always extra challenges for children to stretch themselves. They nurture a love for reading, and if you look at some of the older children's writing it's impressive.
And yes, as you have probably seen already it's a fantastic, diverse community. Even in the "big school" across the road from Early Years all teachers and staff know all children, who are greeted with a smile on their way in.
If your daughter is happy in nursery I would keep her for reception. We did the same years ago and we have no regrets at all. However, if you have any concerns do make an appointment with Mr Weal or attend one of his coffee mornings; he is always very welcoming and genuinely listens to people's concerns.