This comparison to Grange is made by Cambell Martinson of The Wine Front, so to be considered seriously. I also have 2016 and 2018 so will try to try 2016 and see. Both of my friends who tried Platinum 2018 were a bit underwhelmed and picked Pirramimma The Earl 2021 over it. I would say that these Platinum wines really need time to shine.
So if you are going to be patient for at least 4-5 years, ideally a decade, then it is probably a compelling buy.