My DCs go to a similar size school, probably with a similar demographic.
The stats result fluctuate widely - you need to take take into account that, although the average intake is maybe 15, some years will have 20, some will have 10, depending on the age range of the children in the area. For example, my DS (Yr 6) is in a large year group of 24 children, DD (yr 3) has only 8.
In my DS's current year 6 around 7 children will gain 5s, most will gain 4s and a few on the SN register will not achieve this level.
When my DD is in Yr 6, unless there is sudden increase in the numbers in her class, then it is unlikely than they will have a 50% rating for level 4 because out of the 8 children, 4 are on IEP or SN. It doesn't give an accurate reading of the standard of teaching (which is very good, on the whole).
I would try to see the school in action - look at the children, are they happy? are they polite to visitors to the school? Do they answer any questions you might be able put to them? What is your general feeling about the school - is it a happy place and do have the sense that the children and staff like being there?
My personal opinion is that community and happiness are as important as learning for primary years and that with the right input from home, children will do well regardless.