I think a router sled is probably the most precise way short of a CNC. I've had good results in the past using an old no4 jack plane thats set up as a scrub plane, then following it up with a no5 jack or equivalent low angle plane. It's slow and provides a satisfying escape.
What size router do you use (hp), size and type of bit, and how deep can you go on a pass? I like the table setup.