What is the recommended / supported / best way to add a property to a page that is a list of complex properties?
Is it the combination of PTB2 property groups and Itera.MultiProperty? Is there something out-of-the-box in CMS 6 R2? Something else?
There is nothing out of the box but you could try http://episerveresmp.codeplex.com/. It allows you to create collections of custom properties so could be just what you are looking for.