Gustavo: I never claimed that it was realistic for everyone, but it is realistic in our case, and we need to be able to load hundreds of thousands of rows in less than an hour. NHibernate (in more common scenarios) perform roughly the same as EF in our experience, but as nHibernate uses POCO, it is a much better candidate for us at the moment. Maybe EF v2 will change that, but for now, I think nHibernate is our choice.
EF has a huge problem in that it takes ages to manage relationships when you're serializing and deserializing (huge performance problem when using WCF).
