Then i heard about ning and I'm curious what experiences people have had and what downsides there could be to structuring a network with them.

Firstly, who owns the content? If I ever wanted to migrate and create my own code could i bring the content with me or would i be chained to ning forever?

Secondly, i want to integrate all kinds of discounts on products for my members as well as links to my affiliates etc does ning have different terms for sites trying to make a buck?

Any other thoughts, experiences or opinions on ning or other similar services?