I reported converting the CX0 tires on the Superfly to a tubeless setup on October 19. The tires finally sealed-up and have been holding air consistently. I have 336 miles on the set and have noted some tread wear in the center on the rear tire, but they are holding-up well overall.
Today was the first chance I had to run the tubeless setup on the HD Bluff Trails. The last run across the bluff was with tubes and 80 psi in each tire to avoid pinch flats. They gripped and handled well at that pressure, but the back end jumped around like a pogo stick.
Today I set them at 40 psi and rode to the south hill on the road and then jumped on the trail at Hatch road. The reduced pressure made all the difference in the handling and improved the traction both front and rear. They still roll fast through the hard pack and have enough traction to climb the steep rocky stuff.
I think this is the right setup for what I want this time of year though it might get a little pricey having to replace the rear tire every 500 - 600 miles.
I would call the experiment a success in that the 700x38 cross tires improve the road characteristics of the Superfly while making it fast and nimble on the bluff. The ultimate test will be next weekend with a ride planned in Riverside State Park. I will be happy even if they do not perform well in that environment since I do not normally need to ride my bike to the park for XC riding.
I will give an update next weekend after the ride.