"There is also little in the way of research about class size making any difference either."

Uninformed opinion. Here is a list of research on the effect of class size on student performance. This should provide you with years of reading material —

https://scholar.google.com/scholar?q=effect+of+class+size+on+student+academic+performance&hl=en&as_sdt=0&as_vis=1&oi=scholart&sa=X&ved=0ahUKEwiIoMrj8YvWAhUY8WMKHRDABOEQgQMIJjAA