Right let's put this straight.
Be it with or without taking into account the FLEX on the arms, their lenght ALWAYS make a difference in the stiffness of the ARB.
Look at it this way : for a defined angular movement of one of the wishbones, we have a vertical movement of the connection of the ARB that is constant, let's call it A.
If the projected length of the ARB arm on a plane that is normal to the central section of the ARB is called L, then we have the following relation:
cos α = A/L
Where α is the angle of the ARB arm in the normal plane defined above.
As A goes smaller the cos goes smaller too which means that alpha increases.
What that means is that the centre section will see a higher twist rate if the arm is shorter, which in returns means that the ARB will be stiffer.
Now if we consider our R/C ARBs, then you cannot neglect the bend in the arm and that also has an influence on the twist rate. However as the arm goes shorter it also gets stiffer so it all works in the same direction as in the centre section.
PS: can you tell i'm bored at work ?
