i used fondarific and followed the directions included in the package on a small business card. it said not to use cornstarch or ps. however, when i rolled it around the rolling pin to tranfer it to the cake, it stuck together half way when unrolling it. i had to take it off, tearing up the buttercream and making a big mess. i had to redo everything. HOWEVER, when i rolled it out again, i used cornstarch and lifted it over the cake and it was wonderful. i will use it again and again, but i will ALWAYS use it with cornstarch. it tastes great and was easy to work with after my first mishap.
I found in the warmer months, you dont need the cornstarch. When I used it in the cold months, I found it needed some help. It may be different for you in the warmer months.