I am dealing with the same problem and I have one word of advise "asbestos." I was looking at a tool that made to scrape the old texture off when I noticed sticker advising to check for asbestos before using the tool. I took a sample to a lab and it contained between 1 and 5 percent asbestos. According to the EPA, if it's over 1 percent abtement proceedures must be used. We haven't decided how we are going to deal with it yet but we are experimenting with plastering over the texture. If that doesn't work we may just put up dry wall over the old ceiling and use paintable wall paper to provide the texture. Hope I helped, good luck.