I signed with HOED last year, have completed a few mystery shops for them.
I live in Hobart, and the available assignments aren't huge in number, I've gotten about as much work as I expected from them.
You get a good description of what's involved before you commit to taking on an assignment, and the fee is about what I'd expect.
I'm happy with the company. I'd like to get a bit more work, but Hobart is a small place.