Yes! We used Ditra. It was a little more expensive than cement board, but it was soooo much easier to work with! By the time we factored in our sweat and possible doctor co-pays, we decided to go with this stuff.
It's been very easy to work with and has done it's job. Without it, the tile would have been an easy 1/2" higher than the rest of the surrounding flooring.
Tile is a lot of work, but definitely worth the outcome. We plan to finish laying it out today so we can finish grouting tomorrow.
The kitchen heat vent is a problem. We can grout right up to it, but then that eliminates any way of removing it easily. We cant cut out an opening above it and raise it as it's already as high as it can go. The only thing we can think of is to look for a smaller vent register, or cut one to fit.
We decided to put grout in front of it. We've never had to remove it in the 16 years we've lived in the house so probably won't have to take it out. If we have to, we can remove the grout and it will come right out.