I'm going to re-tile almost 800 square feet. I just pulled up all of the old tile that was adhered directly to the subfloor (no backerboard, no Ditra). Most of the tiles popped up with a floor scraper very easily but there was a little bit of thinset left on the plywood.
For the last two weeks, we have been using a floor scraper and a 3x21 (small I know) belt sander to try to get the floor as smooth and flat as possible. It looks MUCH better now but there are still some areas where this is a LITTLE bit of thinset. There are also a few screw heads that are barely sticking up above the plywood. I hit them when I use the floor scraper.
If I use Ditra, do I need to even worry about making the subfloor as smooth as possible, or will the modified thinset and Ditra work ok with a not-so smooth/flat surface. I feel like I could scrape and sand for two more weeks and still not get it down to bare plywood.