Also, I've seen the $100 Freud in stores, and have read that it's
decent (not great, but good). A woodworking class I took had an Oldham
stacked dado, and it seemed to cut clean dado's. Any difference in
quality between the two?

I'm no expert on dado's, but I bought the Freud set you are referring to
last spring for a project made from maple. The results were less than
stellar and I wound up using my table saw crosscut blade to cut both edges
of the dado, using the dado to hog it out, and then using the router to
clean up the bottom. The edges weren't that crisp with the dado set and the
bottom of the cut was far from flat.

So...why didn't I just switch to the router once I realized that the dado
set was not great? Because I spent a hundred bucks on blade set, of course!
;-)

Bob B.