I made two batches of ice cream with dry ice. The both turned out very good. I only put enough in to cover the lower 1/3rd of the freezer. The first batch took about 20 minutes to freeze and the texture was fine. The second batch was a very rich mixture and I wanted to experiment a little. I started out with just the bottom of the freezer covered and slowly add dry ice until the temperature really started to drop. About 1/3rd coverage on the freezer seems to be a good level. My freezer holds about two pounds of dry ice at this level.
It is a lot cleaner than ice/salt!!! and at the end, you can use the remainder of the dry ice to ripen the ice cream.
I consider it a successful experiment!