While it may be true that most people lose their appeals, many do win… so it is worth the effort.
Plus I am still not clear if the in-person appearance is only an option if you are appealing the response to the SOR. That is, your clearance was denied but you were given a chance to reply to the Statement of Reasons; if that is denied, you then have an appeal. Is that correct? Can you also present your response to the SOR in person?
I think most people do the response to the SOR in writing, but some choose to present their appeal in person if it gets to that point.