Thanks, all, for the compliments.
Brice is correct that I was routing slower with the OF-1400. I wasn't intentionally going slower, just trying to push it as fast as I could for a good cut. The 1400 was definitely working harder than the 2200. Frankly, I could have gone faster with the 2200. I wouldn't push the OF-1400 that hard normally.
I'm sure the cleaner 1400 dado is due to both reasons: I was going slower with the 1400 (though I don't think that much slower...) but moreso, you need airflow. The open top of the 1400 allowed air to flow in, stir up the bits, and carry them off. On the 2200, for the most part, there was only a little air getting in from the dado (so a 1"x1/2" opening). I agree, though, usually my dados have curlies in them like the 2200 demo showed. It would have been interesting to do the 2200 dado a second time with the drop-down shroud left up. "Exercise for the reader"

I will say, though, neither dado had chatter and both had dead-smooth bottoms (don't go there...)
The bit for reference was a Freud 4" OL 1/2" D carbide upspiral. The linen-fold is a Whiteside bit, 1.75" CL carbide... a clearance lucky browse that I use a lot.
