As far as I could tell, I used the recommended interfacing. It was the heaviest iron on Pellon I've ever used. The downside of this Pellon was it was so thick, it was almost impossible to get the linen to hold a crease. I used my generic clover clips to help, but I was also working around a lot of beads, so I couldn't use them everywhere. The upside of this Pellon was that the ornament holds its shape very well. The cube is unlikely to collapse, and the distortion from stuffing is minimal. In fact, the ornament seemed so sturdy, I thought about not stuffing it at all.
I am pleased with my finishing. It isn't perfect, but it is close enough that I'm not embarrassed to give it to my friend for St. Patrick's Day. She cross stitches too, so I know she will appreciate my work.