I've seen so many members complain over the years that their double laminated table top warped after they glued it together that I've started suspecting that it's the water in the glue migrating into the substrates that might be causing the warping. 2 layers is not needed. I've even seen Pat Warner say so, that the frame underneath is far more important that what you put on it. I built one table, used it for 3 years, then gave it to my son-in-law who's had it for 4 years and it is one layer of 5/8" melamine with 3/8" deep grooves in it for t tracks and it's still dead flat. Despite going from -45 to plus 40 each year. The trick is a good level frame under it. Theo (Joat) has a table that is at least 15 years old that is a single 1/2" ply that is screwed to a 2 x 4 frame that is still dead level he says. Theo didn't use an insert plate he just screwed the router right to the plywood. You lose about 1/8 to 3/16" of depth doing that as opposed to using a plate. The materials have a minor importance in the build. The engineering is what's the most important.
Someone I consider a master woodworker once told me that a master woodworker is not someone who never makes mistakes. He is someone who is able to cover them up so that no one can tell.