Fluent NHibernate new style mappings - powerful semantics

So today I updated to the latest build of Fluent NHibernate. As any of you who might have done the same have discovered there are some breaking changes. I wasn’t sure I liked the new class based conventions at first, especially since it wasn’t clear at first how to tackle altering my mappings. Then it dawned on me how powerful the conventions would end up being while also promoting DRY.