Class size played a part in our choice. Also both of our kids are at either end of the 'normal' scale', dd is bright and ds (although NT) has needed a lot of support with his language development and behaviour. Both would have had real problems in a big class. The school they are in has half the numbers in the class with a permanent teacher and classroom assistant compared to the local school
Also the school runs a before and after play group, so the kids child care is taken care of, while they play with their mates from school, so I can go and teach other kids! Crazy old world I suppose.
RE the class size with my classes. I teach in a reasonable comprehensive school. Most of the kids are great, with supportive interested families. 'Top' sets, no probelms with disruption, the kids are keen and motivated, middle sets I waste time in having to 'control' the kids and we all have more difficult and less fun time. 'Bottom' sets have the most disruption, with SN kids often having to cope with very, very disruptive EBD children. So the kids who need most of my time get least. Which sucks.