Perhaps this is your answer, then.
Nobody that I know of said that you had to solely use the GG. If using a mirror helps you, then why not just use it? A tool is a tool is a tool. It is there to allow you to get to where you want to be. A mirror is no different to a Fresnel IMO. It is used to make the final image what you want it to be. The Fresnel is there to allow you to see the details; the mirror to see those details the "right" way up.
If you're getting the shots that you're after, I say stick to it!!