Thanks, I'm minded to agree, I only ask as it was suggested as inevitable on another site.
The way I figure it, the arm and hub are traveling the same arc around the the swing-arm pivot so remain in the same relationship, The brake lever arm at the rear-set is in a variable relationship to the swing arm pivot.
My trigonometry isn't up to the challenge but it could only be a few millimetres.
Can't see myself worrying about it