Yeah if you see my video on this build I hold the rack with clamps in it and shake it. Nothing falls out. Its because the bars measures 5/16" and I put a 10 thousands shim between the dado blades just to give it a snug fit but not sloppy so they fall out. And still very easy to pull out.
I highly recommend taking scrap and run your dado at the thicknesses and then start adding shims to see where your bar is still snug but goes in and out very nicely.

Jeff Vandenberg aka "Woodsconsin"