I've installed lots of tile floors. More than I care to remember, and I've used 1/4 Hardi on all of them with no failures. Put a screw every 6" in the grid and it works. The last couple I did I was tempted to use the Ditra, but was in a rust and didn't have time to make a mistake and be forced to back up. Check the floor for any bad dips and humps. Be sure to float those out before installing your backer. Those wood grain tiles are long and skinny, and very unforgiving when a dip shows up. You try to span a low spot and the tiles will break.