I saw the video of the Jayco roof system too and was very impressed. Here's a
to the video for anyone who hasn't seen it. We had some ice and snow here in the Willamette valley, Oregon his weekend. I wasn't worried about accumulation on top of the roof as the density of cement in the video is about 2g/cm3 and the density of ice is .92g/cm3. Even if the ice was packed as tall as the cinder blocks, it wouldn't weigh as much as what they put on for demonstration. Needless to say, the snow came Friday afternoon and was gone by Sunday afternoon. It would have taken me longer to climb up the ladder!