xx.InsertOnSubmit()
xx.DeleteOnSubmit()
SubmitChanges()

and other basic LINQPad advertised as replacement for SQL Management for daily tasks should autocomplete even on the free version for users to get an idea of how well the autocomplete is working.

For example it could be enabled only on LINQ entities and that SubmitChanges(). All other objects should show no auto-complete and on manual autocomplete request an informative buy upgrade message.