I have a few small areas on my ceiling I need to re-texture -- probably a total of 10 square feet. I have tried the Homex canned knockdown wall texture and was very disappointed with the results. Each little texture blob is actually an air bubble. Most would pop leaving a miniature moon-like crater that looks nothing like the picture on the can (not surprising). Sanding the texture after it dried did nothing to fix the craters. Neither does flattening the craters with a trowel after they have partially dried.
So, I am considering buying a texture hopper gun like this one: