1) Exposed seems not an officially supported project.
2) It is mainly based on Active Records pattern which I don't like and don't want to use, so I am not talking about doing what Exposed does, just I like the SQL DSL without code generation idea. Also I think there is also things I would implement differently to make people with Spring background confortable with it.
3) I think it should be possible to use SQL DSL independently of the underlying engine that perform the request.