Has anyone ever used this with the JVC before? I'm interested in any reviews

I have not used one but it looks like it might be hard to use if you plan on zooming/focusing. Also, the hd100 is already shoulder mount so it doesnt seem to offer much except you might be able to hold the camera a little more steady with those handles..

I use this brace made by tiffen all the time and it is just the bomb!

That thing is like a swiss army knife. You can use it for everything. Cool.