Same feel as The Chorus and Avoir et Etre ?

I was just thinking the same thing! I bought L'Argent de Poche a year or so ago and have since hired Avoir et Etre and Les Choristes. I noticed the same warmth and charm and lack of sentimentality that you mention.
I don't know if it is just the influence of Pocket Money, as it called here, or if it is simply the fact that they are French. There is a similar attitude in La Gloire de Mon Pere and Le Chateau de Ma Mere.

How fortunate that great writers didn't merely quote their predecessors! Who, then, would we quote?

For the record, it was Être et Avoir.

All three movies were very similar to me.
Etre et Avoir was a documentary, L'argent de poche was partially
documentary and Les Choristes…
When adult Pierre Morhange read Clément Mathieu’s diary at the beginning,
it made me feel that maybe once there lived somewhere a teacher named
Clément Mathieu. So it was almost like documentary :P
For the nasty pupils he was only a little bit strange and stupid
person at the beginning but soon most of them started to respect him.

Trust and respect is not something you receive with your profession –
you must earn it. You must respect your pupils – at least until they
haven’t done something extremly bad.
And so Clement Mathieu, and Mr Lopez and Mr Richet did.

All three remind us that a teacher can and must to tell to their students
much more than you can find in your textbooks. And all three knew
how to share their knowledge with the children.

Not all the teachers can do it – I remember it very well from my own schooldays.
In some lessons where the teacher was a entertaining person
even the biggest brats were quiet and listening what he or she has to say.
Or at least they didn’t disturb others.