I have posted on your thread before, educator - and I understand why you are still fretting but think that, in a way, there is no more 'outside' advice that we can give as it depends so much on the personalities of your children and the individual schools.
Having taught in a tiny school (about the size that you are thinking of, but 2 classes with a P/T teaching head) I would never send my children to one BUT my children are 'outliers'. Both are very able, and DS has many ASD traits. Even in a larger primary - PAN of 20 but mixed classes to give classes of 30 - DS was the only child of anything like his ability in his year. When in the 'younger' of the two yeargroups in the class, this was OK - he worked with the top group of the year above (though his ASD traits made social things tricky). However, he would have been absolutely isolated when in the 'top' year group in each mixed year class, as those 'learning near peers' of his would have moved on to the next class, as another poster describes. (The solution proposed by the school was that he would move into Yr 3/4 during the second part of Year 1, and keep him there as a year 2, but that is another story)
We moved him to a 60-entry primary, where he and equally able DD have flourished - simply for statistical reasons, they have more children near them in ability, and there is not the same feeling of the children they work with 'moving on' in the second year of a mixed year class and leaving them 'behind'.
However, were my children nearer 'average', many of these problemns wouldn't have arisen.
Very tiny schools - no. Too small a social group, too small a learning group, not enough opportunity for sport, too little contact with a variety of teachers and other adults, very insular school gate politics, continual doubts over financial viability (the 'one year moratorium' on the change in funding that may affect small schools in some LEAs is coming to an end shortly - the school I once taught in is due to lose a massive % of its budget overnight), a focus on nurture rather than extension (gross generalisation, but most people choose small schools because of their small and caring environment, not because they are looking for a streching and academically rigorous environment). But that is for MY children, with the schools that I know. It doesn't help you with YOUR children in YOUR school choice.