Would you recommend EF4 or DataSet for a simple ERP (DB with around 150 tables, WinForm app) that runs on a traditional LAN network (1 server, up to 25 clients)?
There is NO option for LINQ2SQL!
EF4. DataSet is an outdated technology, and EF is in many ways a response to datasets' flaws.
Recently, we created an app that included CRUD operations on 80 tables. We would have utilized Enterprise Library and DataSets in instead of EF. Writing the CRUD procedure and the unit test for each table would have taken us an hour on average. With EF, primarily automatically produced code took its place.