For those interested in writing systems in general (I think Stuart Thiessen in particular) I have just come across another system in France called la méthode Smyle.
You can find more details about it at this website: http://www.signographie.fr/
I've learnt it was invented by Yaelle Pierrat-Frappé
From the very little i can understand in French I think she is in Deaf education, but as you will see immediately from YouTube it doesn't seem to be a very transparent system unlike SW, that woman commenting on the lessons claims it is a difficult system.
Still thought I'd send it to you all for the record.