what is your information source? i think you are allowed to use one link unit and three ads units on the same page
3 ad units and 3 link units in the same page! Your revenue will decrease probably (more ad-blind users).
You can, but I'm curious as to why anyone would want to. I find link units the worst performing, lowest paying, form of product google offers. Three units on a page would certainly lower the product your are putting our there for your readers.