Here is a solid arm that I have seen at shows and have a few on order with the Manfrotto heads. They are also working on one that would extend longer. I am not a fan of the gorliia or the archers choice which I believe is a Gorilla. They are pretty shaky with anything bigger than a GL2 unless they are ratched down so tight they become one with tree. :}
http://www.windevice.com/