I wish I would have found this before. I made marshmallow fluff fondant yesterday and it turned out ok, but all the instructions I found were so vague. I was worried the whole time that I was doing something wrong. Next time I will try this method because your tutorial is explained so much better. Also thanks for posting the shark cake yesterday. Your waves inspired me and saved me from having to make another whole batch of frosting.
It's been a while since I worked with ceramics, but from memory clay is a lot easier to work with. Fondant is quite soft to work with and can be quite limp. If you make a large shape from fondant and let it sit, it will sag and droop into itself. It also has the added issue of needing to be kept at the right temperature/humidity, so if it's in your hands too long the consistency changes. Clay is a lot firmer in the hand and feels more malleable. It also doesn't crack the way fondant does - clay is much easier to keep smooth.