Hi Nic,
No I haven't used one of these. I do have a moose bag that I keep on the front fender during long trail rides but all I have in it is a tube and tire changing stuff. This product does look very interesting though, I might have to invest in one in the near future, b/c it sure would be great to not have to carry my stuff in my fanny pack.
I had always thought it would be great if a similar product could be made to fit in the area behind the shock to carry your tools & stuff in.
I do wonder what they mean by "over loading" though.
Thanks for the post!! Good stuff.