I am planning to tile my guest bathroom floor with Schluter Systems DITRA Underlayment. This is a plastic mat-like material that is used in place of fiber-cement board underlayment, such as Hardie Backer.
I will install it over a solid plywood floor starting with a latex modified ceramic tile thinset, followed by the DITRA, and then an unmodified thinset to set the tiles in. The tiles are a mosaic sheet of smaller tiles in 12" x 12" sheets.
I have seen it used in This Old House episodes, and it appears to work well. Has anyone had personal experience using this substrate material? Any advice or cautions will be welcome.