Aucky - I don't think there is anything wrong with your understanding of VRS but you are forgetting that at high AUM and therefore higher pitch and AoA settings, you are displacing air faster downwards than at lightweights - therefore you must have to descend faster to catch your downwash. This is what Nick has always tried to emphasise, it is all about downwash velocity - a helo of a given AuM with a high disc loading will have a higher downwash velocity than one with a lower disc loading.
You have to move enough air fast enough downwards to balance the mass of the helo and you can do it with a big disc with a large input area imparting a modest acceleration or a small disc working harder with a smaller input area and imparting a larger acceleration.