I don't agree yet that being at a heavier AUW puts you less at risk of VR onset for aerodynamic reasons. With a higher angle of attack on the rotor blades the pressure difference between the top side and the bottom side of the rotor disc is greater; the high pressure side air is more prone to want to escape around the rotor tips to the low pressure side, and thus establishing a vortex ring which quickly deepens towards the blade root. As this happens the equation of lift vs gravity rapidly goes in the direction of gravity.
Gullibell - that vortex is present regardless of stage of flight, as I am very sure you know - but for VRS to occur, there must be re-ingestion of that vortex at the tips and that requires you to catch up with your downwash.
The downwash speed is important regarding how quickly you have to descend to catch it and, although it can vary widely between aircraft types, I suspect the difference on the same aircraft between being at 70% AUM and 100% AUM is probably not very great and probably not measurable with the standard VSI in order to avoid VRS.