Hi - while searching the web for a method of removing texturing off walls, the search engine listed your query from about a year ago. Did you ever find success? I actually had a gallon of Texture-Off, actually made by Zinsser about 5 years ago. It worked pretty well then, and worked fairly well last week until I finished the can. I contacted Zinsser and they told me they no longer make it. Every home center/hardware store I ask thinks I'm from another planet. Next I'm going to experiement with Citri-Strip - at least it won't smell as much as other paint removers.
In one closet I knocked down the high spots with a cheese-grater-type sander and an open-mesh type drywall sander, then applied a skim-coat of plaster. In another closet I used a thin coat of drywall mud. It did a 'fair' job, without adding too much thickness. Not super-happy with it, though.