Personal preference,

My take: One class per classlib means it isn't a lib. It's a class. Why even have the classlib at this point? A class should have one purpose and one purpose only. This is called out in the Single Responsibility Principle (read about it at http://www.dotnetcurry.com/software-gardening/1148/solid-single-responsibility-principle) A classlib should hold *related* classes. For example, a classlib with stuff for a form should have nothing but stuff for a form. Nothing for reports.

>I'm seemingly the biggest proponent of having only one class in a classlib. That is exactly the same as saying having only one screen in an scx. I just name the class and the classlib the same.