Personally, I would go for the smaller school with the multi age classes.

I have taught in both a small school of around 230 students and a big school of over 700 students. The environment of a small school is beautiful. Children make so many friends and learn how to play with children of different ages - this improves their social skills. It was so great to see children in year 4 and 5 letting yr 2 and 3 kids play soccer with them in the playground, etc (which would never happen in a big school)!

In regards to learning environment - I agree with Tanstar. Your child will benefit in all areas whether she needs extra support or is working above grade level if she is in a multi stage class. A lot of work is done in groups with children of the same ability so your child will be working at her level.

If you can, try and be as involved as possible and volunteer for reading or maths groups so that you can see how the classroom runs. Parent helpers are loved by many teachers and are a real asset in the classroom.

Good Luck with your choice. Maybe speak to some other parents whose children attend the school to get some feedback from their point of view.