I usually use a router to make dado cuts, but there are some uses like lap joints that are better to do with a dado head.  The Freud 508 set is less expensive than Forrest's Dado King, but it got a good review in Fine Woodworking, so I ordered it.  It's been several years since I've used a dado set, and now I remember why -- setting up is a bit of a pain.  But...  I tried making lap joints once on a router and had to interrupt the work with a trip the emergency room for a few stitches.  To get reacquainted with dado sets, I made some 3/4" wide x 1/4" deep cuts with the Freud set in some scrap walnut, in melamine-clad particle board and in cherry plywood. The cuts  were perfectly smooth, with a perfectly flat profile and no tear-out at the exit.  Very impressive that it can handle such different materials.