I'll be using 12" x 12" tile. And I bought a roll of Ditra months ago, so I guess I'll have to find some un-modified thinset somewhere. I had a bag of 317, but it was 2 years out-of-date and had to return it. I guess the Laticrete un-modified just isn't a big seller around here. Are there any other brands that are good that I should look out for?