Oh, I have done this a little bit since I don't have so many sbd, I am not sure I want to go to the next level because when I want to buy back sbd with the steem that I have got from converting sbd, I get less sbd. For example, I converted 1 sbd I got 2 steem, but when I want to buy sbd with this 2 steem I would get 0.8 sbd.
By the way, thanks to @runicar for introducing this to me, but your video making it easier to do via steemworld.